It comes to not surprise that there is a sucker born every minute and that we can all sometimes get sucked into the game. It certainly can feel that way, the rules are unfair, the game is rigged. Just look at the screen shot of an experience I had on online poker.
There are many vulnerable markets out there in gambling, card counters, angle finders for roulette, weighted dice. Anything that gives you the edge makes you the casino. Of course if everyonnnne knows about it then the edge is gone or sealed up. Which is why you need a niche! It used to be the bookies would hedge their bets so the book was even and the spread was good, sadly this is no longer the case with book making.
The way it works is they ban anyone who has any slight appearance of them knowing what they are doing, (the exception been pinnacle or bet fair) which are high volume or percentage of all winning stakes. The key with gambling is to make mathematics your friends and get positive expectations, there are markets out there to exploit!