It might because of the eagerness to recover what you have lost. Even we set a limit on how much to spend for the duration we're going play sometimes we dont follow it. Losing the money is depressing thats why its hard to stop and in the end you have this regrets why you gamble the money instead of spending it to buy food or other important things. But we have different way how to handle such situation and it depends on the mindset of a gambler. Its much easier to stop if you win rather than if you lose.