I am sure in this case that there's no gambler that would give so much interest with his money in placing bets in games he is oblivion about. We play to win buy then how do we win if we're playing blindly ? And that's why every gambling plays only games he has more winning advantage on because that's where his strength lies.

Another reason could be that they get so much fun from playing those kind of casino game or sports game. Mind you not everyone plays because he wants money, some persons do so due to how interesting and fun such game's gives them and how skillful they're with playing those games.