If you want to gamble, see it more like you are paying the casino or gambling platform to have some fun (just like you do to go watch some movies in cinema), which if you are paying for anything, you are not meant to expect it back.
If every gambler thinks this way, no one will go home with a sad face thinking that they we're robbed by the gambling site. Problem with other gambler is they made gambling their way of life, they make a living out from it, daily they go to casinos or visit gambling sites thinking they can beat the system and get profits.
Yes thinking like this some of them really lose their money while hopping for earning it, the mistake most of gamblers use to do is they take it for fun not as business and serious way to make money, here you will not rely only on your luck but will have to use skills and knowledge too, but we cannot force anyone just let them make their own decision but really hopping for the good.