I don't think in the long run you can make a profit even though you keep control on yourself but you can reduce your loses for sure. All types are gambling need a some luck in the long run and without luck one can't win every time so gamble only for fun and invest some other places for earning profits.
It only means that whether on the beginning or longer period of time of betting, what matters most is the players attitude towards the game. If he becomes lazy and greedy, then for sure, he will lose the game. But if he remains composed and follow the planned strategy and knows when to bet and stop, then he might win in the long run just like the professional gamblers out there.
I agree on this partially, because I don't have trust in slot games here no strategies will work. Only luck matters. But yes in skill games like sports betting, poker we can use our strategy. And here if we know which game we have to bet and which odds we have to choose, and we have self-control means there is a possibility are there to win in the long term. But I am not sure.