That is subjective. There are no exact figures that we can consider as an amount we afford to lose.

For example, we put a threshold of $500 as an amount we afford to lose. Let's say unfortunate things happened and we lose that amount, surely we will not stop as we think we can still put up another bucks at risk as we know we afford to lose that amount. And the rest is history.

It doesn't matter if a gambler bets more than they afford to lose. Their money is their rule.

However, while they are crossing their limits, make sure that they are still responsible enough for their financial status outside gambling. In that way, everything is balanced and life outside gambling is not truly affected even how hard the gambler is. Professional and experienced gamblers are like that.