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Decisions Vs. Outcomes: The Dark Side of Lucky Investment Outcomes

Jake - Author/Founder

Hi. I'm Jake, a frugal Canadian Engineer. I believe you can build a great life through frugal living and index investing.

Understanding the difference between decisions and outcomes can make you a better investor. It can keep you focused on processes and things within your full control. 

Consider Fred who takes his life savings and throws them down on the roulette table. Fred doubles his money.

You likely agree that this was a terrible decision, even though it resulted in a good outcome.

A good outcome doesn’t always reflect a good decision. And you can make a good decision and have a good outcome. 

So what’s the difference between the quality of the decision and the quality of the outcome? 


Short-term investing outcomes are random. You can’t predict what will happen in the market in 1-5 years. As time goes on, your investing outcomes will start to align with the quality of your many investing decisions. 

When investing, it’s key to detach short-term outcomes from decisions. This separation of decisions and outcomes is at the core of stoic philosophies that have stood the test of time. 

The concept applies to life. Not just investing. 

Infographic: Decisions vs Outcome
Infographic: Decisions vs Outcome

Table of Contents

Biological Basis for Learning – Good Outcomes

Your brain releases dopamine when you have a nice result. It makes you feel good, and it tells your hippocampus to remember the behavior that led to the good outcome.

You learn.

Not only do you remember the behavior, but you also remember the “trigger” conditions for which the behavior occurred. Here is the process:

Trigger => Behavior => Pleasure => Remember => Repeat

Examples of the dopamine system in action:

  1. Take Break (Trigger)
  2. Smoke Cigarette (Behavior)
  3. Pleasure (Dopamine)
  4. Remember the Break (Trigger) and the Cigarette (Behavior).
  5. Repeat.

Another Example: 

  1. Drive Past Casino (Trigger)
  2. Gamble (Behavior)
  3. Win Money (Lucky Outcome)
  4. Pleasure (Dopamine)
  5. Reinforce Behavior (Learn).
  6. Repeat. 

How a Lucky Outcome can Reinforce Poor Decision Making

Now, let’s look at what happens when you make a poor decision and have a lucky outcome. 

  1. See hype around a stock or asset (Trigger)
  2. Invest large fraction of your wealth in hype stock (Behavior)
  3. Hype stock goes up, you sell high (Lucky Outcome) 
  4. Pleasure (Dopamine) 
  5. Reinforce behavior (Learn)
  6. Repeat. Attribute win to your “skill”. 
The individual who has this lucky outcome will be more likely to concentrate their (larger) portfolio value in the next hype asset. 

After all, the emotional pleasure response of a good outcome has reinforced the original actions of investing in speculative assets. 

Armed with overconfidence, this investor is well positioned to destroy a portfolio worth several decades of income later in life. 

A lucky outcome based on a bad decision waters the seeds of overconfidence. 

Outcomes Vs. Decisions

A bad decision can result in a good outcome due to good luck. Conversely, a great decision can result in a poor outcome due to bad luck. You can see how this applies to short-term investment outcomes. 

A bad decision, if repeated, is expected to lead to a bad outcome. And a good decision, if repeated, is expected to lead to a good outcome. Repeatability reduces the role of luck, and aligns the decision with the expected outcome. 

An Expected Outcome - Example

Consider a bet on a coin flip. You win $50 if you flip heads, but you lose $100 if you flip tails. This coins (like most) has a 50% chance of heads and a 50% chance of tails.

Your expected outcome is: ($50)(50%) + (-$100)(50%) = -$25. You have an expected outcome of a $25 loss per flip. Engaging in this coin toss is a bad decision if you want to increase your wealth.   

You could get 5 heads in a row and win $250 – a better-than-expected outcome due to good luck.  Or you may get 5 tails in a row and lose $500 –  a worse than expected outcome due to bad luck. 

The contribution of luck will reduce as the number of trials increases. If you repeat the coin 10,000 times, you’ll almost certainly end up with the expected outcome of a $25 loss per toss, or $250,000.

Bad Decision, Good Outcome

Here are some examples of bad decisions with lucky outcomes.

  • You go to the Casino and throw 80% of your life savings on blackjack. You double your money. Great outcome. Terrible decision.
  • You put 70% of your portfolio in Bitcoin in August 2020 after seeing great returns and feeling FOMO. Great short-term outcome. Bad decision.
  • 100% of your savings are invested in the stock market and you need your money in 3 years to buy a house, and In that time, the market goes up by 40%. Good outcome, bad decision.
  • You consistently buy lottery tickets to hopefully increase your wealth. You win the jackpot. Bad decision, good outcome.
If you repeat these decisions over and over, you will wind up with a bad outcome – that’s what defines a bad decision. 

Good Decision, Bad Outcome

Good decisions, when repeated, will likely result in a good outcome. Here are examples of good decisions:

  • You just start investing in 2007, and put your money in an index fund. The market crashes over 40% over the next year. Good decision, bad outcome.
  • You receive a $50,000 inheritance and you do research on lump sum investing versus dollar cost averaging. You find lump sum investing outperforms DCA over 60% of the time. Based on research, you decide that lump sum investing is best for you. However, the market crashes 30% the next 6 months. Good decision. Bad short-term outcome.
  • You continue to invest in indexed funds while your friends invest in hype assets. They are growing their money much faster than you in the short term. Good decision, bad short term outcome.

Bad Decisions, Good Outcomes, and Overconfidence

The combo of bad decisions and lucky investment returns can fortify your natural overconfidence bias. More overconfidence means more bad decisions. This bias is especially strong for young men. I know this from experience.

When outcomes are good we over-weight skills and abilities. Obviously investing in TSLA at the bottom of the COVID crash was 100% skill-based, right? We tend to underestimate the role of luck in these cases. 

When we have a bad outcome, we over-weight bad luck and tend to shift blame from ourselves. We tend to over-weight factors outside of our control to explain bad outcomes. This keeps our ego afloat, but it comes at the cost of overconfidence and a missed opportunity for personal growth. 

A good outcome based on a bad decision will reinforce overconfidence. This is a rough road because overconfidence becomes more dangerous as our portfolio grows in size.

The Recent Bull Market and Over Confidence

You, like myself, may have started investing in the 2010s. We have seen unreal returns, far above average. We lived through one of the largest bull markets in U.S history.  We missed the pain of the dot com crash and 2008 crash. Our only crash was during the first COVID wave where the quick rebound was relatively painless.

Overconfidence peaks at the end of a strong bull market, at exactly the time when expected future returns are lower due to high valuations. The last decade of investment returns can breed overconfidence. I am worried that this has caused many to take on way more risk than they can tolerate.

What is a Good Decision?

A good decision maximizes the probability that you’ll meet your unique goals (outcomes). 

Good decisions are likely to result in a good outcome when repeated.

Ultimately, a “good outcome” is defined by one person – you. And it’s based on your unique values and goals. With a good decision, you’ll gain the highest probability of meeting your unique goals.


Bloggins has an investment time horizon of 25 years, expects a stable military pension, and has a high awareness of his human biases.

Joe has a time horizon of 5 years, expects no pension and doesn’t have much earnings power (human capital). In addition, Joe doesn’t like volatility and values stability.

Investing in 100% stocks is a good decision for Bloggins. But it’s a terrible decision for Joe. They have different goals. In this case I don’t even account for differing values. 

The Role of Cognitive Bias

Us humans have many of cognitive biases. Understanding these biases, and how they affect you, will help you make better investment decisions. 

This will help you take on an appropriate level of risk through proper asset allocation.  To learn more, check out my post on common cognitive biases, risk tolerance and asset allocation.


A good decision is not always equal a good outcome and vice versa. Huge investment returns – a lucky outcome – based on poor decisions can fuel overconfidence. This facilitates more poor decisions, which can result in lower future returns, and even significant losses later in one’s investment career.

Losing money early on in your investment journey may help you get in tune with your cognitive biases. It’s a blessing to be humbled early in your investment career.
As always, an understanding of your weak points and knowledge of self will help you preserve and grow wealth over time.