It's not everyone that becomes addicted to gambling, only those that lacks self control and also those that have misconception about gambling are the people that easily get addicted to gambling. It's been said that anybody that can not handle their emotions during gambling should avoid gambling because they will lose more money than expected and they can also become addicted which could cause a big harm to their well-being. Gambling is based on luck and people who understand better are doing fine without being addicted.
Not everyone who has lost more than planned becomes addicted to gambling. A big loss can lead to disappointment and a person may decide not to play anymore because of this. Luck is just one of the components of success in gambling, and luck is a fickle thing, today it is there and tomorrow it may not be there, so in addition to luck, you need to be able to act according to the situation, and be able to stop when you see that this day is unlucky for you.