I think gambling is addicting because of that feeling when you win big time! Not many things can measure with the thrill when you win at dice or even sports betting. I have increased my bankroll couple of times in my life by 400%-500% and these kind of winnings make you an addict.
That feeling of winning big time is making us to be popular in the web or chatbox but that's not really the reason why gambling is so addicting. Gambling is simply addictive the way it used to be. We are winning and losing and upon experiencing to win that much it's making us more happier and feels comfortable that next time we gamble we'll win again. And that practice is repeated until it becomes addiction.
I think this gratitude/validation from others is just making the whole gambling thing even more addictive but it's not really the root of it becoming addictive. In our life, we have this thought hard-wired to our brain that earning money is really hard. It is indeed hard. Some people even believe that earning a good amount of money are only for those people that are smart while some believe that it's only for those people that have the connection. In gambling, you can earn money in an instant. And by instant I really do mean instantly. With just one click of a button, *drum roll*, and you'd know if you have successfully made money from the money that you risked and what a job it brings when it works out for you.
As time goes by, you start to have gambling buddies and you guys congratulate each other whenever you win something or whenever you do something risky and you won money. It's a loophole of you hoping to feel that excitement/validation/happiness over and over again but the truth is that you are paying for it by losing your money from gambling. You don't really feel that you are losing money because you are still happy. Happy that you have had that excitement even for just a split second moment.