I would say there is no such thing as "the exact moment". First one wins, decreases bankroll/max bet, other bets get cancelled or whatever it is that the site would do if someone tries to exceed max bet.
Exactly that.
Bets happen one after the other. The site would make a note, after each invest/divest event, of what the bankroll needs to fall to for the next investor to get force-divested, and it would do so as soon as the bankroll hit that level.
The idea that 10 bets happen "at the same time" isn't real. Sites use locking to make sure that doesn't happen. Or sites get exploited.
