> specifically mentioned "bettors" - day traders/speculators, not long time investors

Forex is zero sum before fees and negative sum after. It’s distinct from capital markets. I wouldn’t extrapolate losses from FX.

It's the same loss percentage for stocks day trading. The loses do not come mainly from the zero sum/fees, they come from the lack of alpha.

> Depending on the source, only around 3% to 20% of day traders make money. But that 20% estimate probably has as much to do with the time period studied—the dotcom bubble. It's hard to know for sure, but it's probably fair to say that up to 95% of day traders lose money.

https://www.investopedia.com/articles/active-trading/053115/...