Why do you think drinking and smoking could be easily triggered by loneliness and not gambling? Gambling could be triggered same way drinking and smoking could be triggered when someone immediately loses his spouse and becomes lonely overnight.
Even someone that has not gambled before could pick up the habit when lonely. And with no significant other to talk some sense into him, he could go over board with his gambling activities. I think someone could easily pick up the habit of gambling as one could pick up smoking or drinking when one suddenly finds himself lonely.
I am talking from experience I mean to what has happened to me and I didn't turn into gambling addicts rather was propelled to go drink, I tried all I could do control this but couldn't that was when my fiance left me and it happens that I so much love and cherished here. She was too dear to me and she go just like that even when guy experienced same thing he just turned out to be a drunker why didn't he go into gambling?
The major point here is already such person had gambling in mind or is already an addicted gambler so his condition just makes it worst instead of controlling himself. Okay let say if someone is lonely where else do they go to make themselves happy, is it not party and during partying you got drunk and go back home so why gambling?