Sometimes they need to read of their so-called confidence things if it has to do with gamble, it can make a gambler to lose huge amount. Image when you become so lucky to cashout from jackpot that you didn't expect and you becomes so confidential (quietly continue betting) and keep on gambling, unfortunately you will lose the money you through jackpot. This is why one have to quite if he is lucky to win huge amount.
but indeed being too confident in gambling can actually make us experience disaster, because excessive self-confidence makes us believe that we can get victory for sure while in reality it is not like that. The victory obtained in gambling is certainly one of the things that can attract gamblers to gamble further, as you said with the jackpot. Of course when someone gets a big win or jackpot there must be a desire to bet again, and maybe if they lose once or twice it doesn't make them stop betting.
everyone has a different personality, so when they win they must have different thoughts. some may prefer to continue betting even though they have had time to cash it, and some prefer to cash it and then leave gambling to enjoy the victory. people who can be calm when they win are the real winners because they manage to control themselves including by utilizing the victory they have obtained. It must be admitted that when you win, of course adrenaline will be stimulated and it is not strange that many continue gambling again and again.