The story of a ByteDancer making $30 million and retiring precisely activates a factory-installed bug in our brains.

Let's start with something counterintuitive: Why do we still get excited when we see it, even though we know it's luck?

This news has been all over social media these past few days: A ByteDancer trading stocks, turning their first pot of gold from options — $20k rolled into $200,000, and finally made $30 million and retired. When I saw it, my heart also skipped a beat. Rationally, I know luck played a huge part, but that urge of "maybe I can do it too" is still hard to suppress.

Later I figured it out. This news went viral because it precisely hits a factory-installed bug in our brains. This bug is hidden in one word: ergodicity.

That person rolled $20k into $30 million — that's the result along one timeline. But think of it another way: If you let 10,000 people each use the same strategy of betting their entire net worth on options and run through it independently, what would be the average outcome for these 10,000 people? It would be zero.

Because with this strategy, if you blow up your account just once along the way, that timeline is permanently out — you can never come back, and no matter how large the subsequent gains are, they have nothing to do with you.

And the key is right here: an individual's long-term fate is roughly equal to the bankruptcy version of the average fate of a group, not the average return version. That's why a gamble with positive expected value can still make you go bankrupt in reality. Because you only have one account — lose once and there's no next time.

Our brains default to calculating with paper expectations ($20k to $2 million, seems like a good deal on paper), but forget that we are living on a single timeline (lose once and there's no next time). The excitement comes from right here.

Never use the average of a group to make decisions for yourself, who has only one life.