Gambling addiction starts by first playing for fun but when you lose high you start to this k how you lost and then you do more gambling and then this way you become addicted to gambling in recovering you're loss.
So the theory is that everything is on gamblers will to kill his full investment or forget the loss and leave with what left and live happily
I think some people are just born with a more addictive personality which causes them to get easily hooked on gambling. It isn't exactly the same but alcoholics tend to follow the addiction pattern of their other family members so we shouldn't put too much blame on individuals. Quite frankly, as long as they aren't harming other people I don't see a problem with it.
Well sometimes they can't help themselves. Other people like friends and family members will eventually be dragged especially if the gambler has lost all reasoning that it compromises financial and family affairs.