I think the answer is in the question. They're not playing to win money. They're playing because whatever rewards that have been engineered into the game suck them in. Social aspects, FOMO, "winning" at a game, etc.
Different people crave different rewards. Some people may care more about the financial reward, but they're out playing some other gambling game that caters to them.
Different people crave different rewards. Some people may care more about the financial reward, but they're out playing some other gambling game that caters to them.