There are winners and losers always. Gambling, trading, investing they are existing and together combine to make up what we have: the market, the gambling community. Gambling sites can not operate and survive if they only run with losses. Gamblers don't make deposits and bet if they don't win any single bet. Gamblers win and lose but the final result each day or each month make sense for their balance.
It is not the responsibility of gambling site to guarantee their customers (gamblers) will end with losses, wins or draws. They only provide Provably Fair gambling site and games, the rest responsibility is for gamblers: Gamble responsibly and manage their fund.
I have always found that to be interesting topic. There is a thing in gambling where if you reach to a casino and say that you are a gambling addict and you should be banned, they ban you and never let you start another account again. That sounds moral and ethical when you say it like that, but if you rephrase it and say "I am a customer who you will make a lot of profit from, in order for me to not profit you from now on please deny me your business and agree to lose money in the future because of it" and you will end up something weirder.
Let's say there is a very fat person, and they walk into a cake shop, does that cake shop deny them their business because they are already too fat? Of course not, they would be happy to give them all the food they would want. This is why I never understood that gambling addiction type of deal banning people.