I prefer play with profit but if i win a lot of profit like 50% of my invested bankroll then i will stop playing for that day and play another day because i've always experienced in the past that every time i play longer i always bust everything.
Longer the time you spend in a gambling site the more chances are there for you to bust and it is simply called house edge
I would book my profits and keep the initial capital away from the gambling site as you never know when you are going to be busted.
it's same thing i guess , when you decide to play with your profit or not. as sooner or later you would make a comeback and gambling again with that profit fund. unless if you quit forever from gambling after the last winning , it would has different story. so there is no difference for me.
It is difficult to find a formula to know the right time to play and the right time to stop. But in practice, what you see is that when the individual makes a lot of money, if he/she keeps trying to increase the gains in general this brings losses after a certain point. Some people make this mistake by not knowing the game, others make these mistakes out of greed, in both cases is necessary to have a greater level of knowledge and discipline to prevent this from happening.