I think yes, gambling can be profitable for long term. The problem is many people can't do this if they can't control himself on gambling and greedy. To get profit in long term, you need to keep on track by do research on every match that you want to bet.
Well i don' t think that would be applicable in most gambling games though. Like for example dice, how do you research the rolls there? It mainly depends on you being lucky if you're going to win. So there may be profit in a few gambling games but generally i don't believe gambling is there to be profitable for the player