I know that as gamblers, everyone can relate to this question, as we have surely experienced it in real situations.
Suppose our bankroll is $100 and it has already grown to $500, would you quit or continue? Conversely, if with our bankroll, we are down to $10, would you still continue or save the remaining $10? I used specific amounts to make it easier to discuss this situation. I understand that we all gamble with different amounts based on our income, but consider this as an example. You can mention any amount you want based on your personal experience; it doesn't matter.
It's easier to quit gambling when your losing, we all have to agree that losing actually sucks and it comes with a lot of depression, finding yourself in this state might make you consider taking a break or quitting entirely..I haven't seen people quit gambling from having constant wins, instead it gives more drive to continue gambling, greed is part of our nature as humans, we would always want to to get more because our needs are insatiable... it's easier to quit when losing than winning