[fifilura]

It is a fun story but it does not have to be true.

I think von Neumann would understand some basic probability already by then.

Or maybe not? But at least there is a non-zero probability that it did not happen like that.

[TeaBrain]

By that time he'd already created the foundations for game theory with his minimax theorem of zero-sum games. I think its more likely that he knew was he was doing and expected to lose the money.

[in3d]

Old roulette wheels had large flaws, even in the 1960s: https://thehustle.co/professor-who-beat-roulette. 30 years earlier they must have been worse. So there is a chance he noticed some anomaly that he tried to exploit.

[TeaBrain]

That article was a good read. That is a possibility.

[gumby]

Sure, he would have known probability, but apparently he knew how to make up a good story to charm someone.

Sounds like his losses were a good investment.