Some ppl gambled for fun that's how their addiction started. If they're gambling with the correct mind it isn't going to become a problem but if their mind gets addicted to gamble it's going to change their life for ever. When you gamble you're going to lose money the companies don't.
Everyone has their own reason of gambling, either it is for fun or to double their stake amount. And some are playing gamble to pass time. Those who are playing gamble to pass time would say when they are at home alone, it is too boring and that made them to come to visit the casino center or visit the casino website to play some games to pass time and in the process, they win more that would continue everyday before he new, he can't stay without gambling and from there he became an addicted gambler.
That was why many here have said that gambling addiction is from the gambler's mind. He could have prevented it at the beginning but he was motivated by the games he played.