There are professional texas holdem players. It's largely based on mathematics at the pro level, but also to recognize human behavior, ego, patterns etc. which at a pro level they will always switch it up or "balance their range". To say all gambling is a loss in the long run is just ignorant of the skill games. Games like roulette and slot machines are of course rigged for a house advantage, but in poker against other people the house takes "rake" which is usually like 1-2% of the total pot. Or if you're doing tournaments you buy in for $10 +$0.50 or whatever their rate is.