Being addicted to gambling, drinking, clubbing or any other things also depend on the environment you are brought up and the manner in which you were brought up. Some people are trained to be disciplined and learn where to cut the thread. When a habit is becoming repetitive, you should know and caution yourself. But most times it is difficult to control when you have a group of friends who influences you and in such a situation the remedy is always to relocate and have a fresh life somewhere else in a different environment.
There have been many studies made which show that people do in groups things they would never do when they're on their own, this means that even if you have a lot of self-discipline if you happen to go with your friends to a casino then you'll have bigger chances of betting way more money than what you can afford to lose, and if to this we add that you're more likely to drink alcohol as well then this can be more than enough to make you disregard your upbringing and lose a lot of money in a single night.
Yes, I would never advocate that a gambler will always be able to do responsible gambling. His gambling may also change due to various factors. Those reasons could be drinking beers at the casino with friends and then gambling recklessly or gambling on your own. Sometimes he spends more than he can afford. This happens to most gamblers. And this is considered normal behaviors of gambling.