According to me gamblers enter casino and bet to earn money. I don't see anything wrong here, because if a gambler is limited to a certain budget, then losing money won't be much of a loss. But when a gambler bets unbridled for excessive profit, loses all money and becomes depressed. A fixed budget and a time limit should be set to avoid these problems. Then he will be able to stay in discipline. In my opinion it is not good to have too much confidence in gambling as it depends entirely on luck.
While I agree that having a budget and time limit can be helpful, I think another thing many people don't think about is that discipline is easier when the everything is going smoothly but get harder when the emotions are in play. You might have a wagering limit that you set before the game but after some series losses or a major win, all those limits a person set might not be important to them anymore.
Which is why it's very important to for a gambler to always manage their mindset just the same way they are managing their bankroll. The hard part of gambling is not about setting rules, the hard part is sticking to your rules when temptations shows up.
Every gambler have set one or two rules before gambling, but the moment things start getting very bad for them, all those rules became less important. For me, once I notice that the game is getting bad with series of losses, I will just walk away.