Once you got profit then just stop it. Because if you change your profit to a percentage you could control your greed.

What if you don't get profit then will continue until you get a profit in gambling? Don't ever plan to gamble until you get profit but also try to set a limit for your losses. If you lose a certain amount then should stop gambling and come back again some other time. Setting limit only for profit may lead to losing a lot of money in gambling don't do that mistake.