From my (limited) experience watching folks at the roulette table, I think there are two kinds of players.

There's the players making small bets, they win a bit, lose a bit, and at the end of the day they may go home with a bit more or a bit less money than they came with. The casino wins on average because of the 0.

Then there are the gamblers. They come to the table, make a few large bets, and within a few minutes they lost their monthly salary (or whatever was the limit on the ATM). They lost because the player will continue playing until they can't.

I'm pretty sure that you could make a completely fair roulette, and the house would still win big every day. I'm not sure why there aren't any fair roulettes, though.