This usually starts when someone looses his money/BTC in a gamble
Experiencing the happy days of gambling, winning big amount and then suddenly you lose most of it. That will crave you of getting back those bucks and it will start you to pursue to gamble and give more time in gambling which results to addiction.
because if you have experienced winning a lot you are thinking that you could do it again somehow that could make you really focus to gambling again. It's that feeling making you want to gamble again and again and it's probably addiction already. In the end you could lose everything.