- Even if a game is played sticking to optimal strategy, odds are in favor of the house. Through game rules, and/or house rules.
- Many players are tourists that do not know how to play optimally. Those subdize players that win, and leave a margin overall.
- They encourage drinking by offering alcohol for free to make people less inhibited, less risk averse and diminish their ability to play to the best of their ability.
- There are cognitive biases that create the perception of a higher probability of winning: https://en.wikipedia.org/wiki/Gambler%27s_fallacy
- Players do not use currency directly, but chips. Chips have a more playful connotation than currency, and create a level of indirection that subconsciously distracts people from the fact they are dealing with money.
Then, some personality traits and mental health conditions can contribute to less risk aversion and other aspects that lead to unreasonable gambling.