Personally I am into gambling not to win a jackpot or earn huge money, I gamble for fun just to earn some extra funds thus I only gamble with small amount of money the amount of money I can afford to lose,~
There are many reasons why people choose to gamble and the reason they get addicted also varies. We need to set a baseline standard that addiction is no good. So for whatever reason someone might gamble, and if it reaches the point of addiction, they require further help.
Nevertheless, to set a specific reason for loneliness as a cause based only on OP's story, I think it lacks nuance context. We can not know for sure what is the trigger that makes OP's friend decide to play gamble. You might say that you are into gamble because of this or that, but, it is tricky to put yourself on the some else's shoes.
Yes that's right, of course there are many reasons and factors that can make a person a gambling addict, it's very much and if I have to write it, it might take a lot of notes just to write the many reasons and factors that can make gamblers addicted. On the other hand, yes it is true that we must set the idea in ourselves that addiction is very bad along with always applying awareness firmly in every time you gamble, it will help you to slightly prevent addiction.
Although the case experienced by the OP may be for some people it is not very nuanced but in my opinion it is very possible and still plausible to happen, and it seems that the OP has a little relationship with some people who are actively gambling, so when he finds enough free time that makes him feel lonely then a curious feeling arises to try gambling like some of his friends do, according to my assumptions and my predictions it seems that the scenario is like that which triggers the OP to finally choose to gamble.