First and foremost, gambling is always depend on luck.
Gambling is definitely a game of luck. But here we are talking about sports betting. Sports betting can be considered as both game of luck and skill. As in sports betting you need to analyse the sports event, do calculations and then only bet in it. So if a bettor is losing, then it only proves that he doesn’t have required knowledge on that particular sport. To be honest, now for a few days I haven’t seen many gamblers losing money on sports betting, yes they bet on odds with less returns, but never seen losing more than winning.
I definitely agree with your statement.
At some point, the curve will definitely be in favour of the gambling platform given that there is no absolute result when it comes to gambling. It is either you win or you lose; the more you engage yourself in a very risky environment, the more you put your resources at risk.
This explains on why majority of the gamblers who continuously gamble (despite them winning a large sum of money) lose their resources at the end. If you truly want to maximize your winnings, better that you invest the money you have won.