My vice used to be online poker (NL Texas Holdem) but I didn't really call it gambling back then. Back in the heyday around 2006-2008 it was honestly like printing money. Easy $$$. Anyway, as the competition got more fierce my bankroll management slowly went out the window. I started losing a lot chasing those big paydays that used to come easily. Long story short I managed to get pretty much my whole identity caught up in this idea of becoming a professional online poker player. Several of my friends ended up dropping out of college to pursue this dream with disastrous results. When it was good it was good but the downswings were brutal. Definitely possible to be profitable over the long term if your disciplined, but the stress was eating me alive not to mention fueling all my other vices like partying. Drink away a big loss, celebrate a big win, etc. No way to live. It takes a special kind of person to succeed in that world and to be able to grind it out day after day without imploding. Even among the most disciplined players, the addictive nature of the sport along with the allure of the big win will cause almost everyone to self destruct and go bankrupt in the end.
The only people I have ever known to be successful longterm in poker are those who are being staked by investors. Playing with someone else's money takes a lot of stress out of the equation and adds a layer of accountability which helps one practice discipline and proper bankroll management. Although, in order to get to the point where someone will stake you is a long road in and of itself and often involves quite a lot of luck.
One thing you should know about playing blackjack, roulette, and slots on the online casinos is that it is quite literally lighting your money on fire. It used to be a well known fact among the online grinders in the poker community that the casino games were heavily rigged. Despite what the sites will tell you these games are not random chance like they'd have you believe. Most of them have carefully engineered algorithms designed to cheat/screw you out of your money. Due to the lack of regulations in the online industry there is simply no accountability and thus no reason for them to practice integrity. I remember back when Party Poker was still around I decided to play the black tables and all was good for a while, slowly winning money. As soon as I decided to up the stakes, BAM the worst bad luck streak ever. If I remember right, the odds were less than 1% of having a losing streak that bad by chance alone but somehow in a matter of about 15 minutes I managed to burn through over $2000 on $100 and $200 bets. That was a wakeup call.
At least in online poker you could be pretty certain in most cases that the house wasn't screwing you. They just took their little cut out of every pot and were satisfied with that. Even then you still had the problems of bots infiltrating the games every now and then, or rogue staff who had cheating software that allowed them to see other players cards. In addition, you had the fact that some of these sites would just randomly ban players and steal their money without any notice or justifiable explanation. Even Full Tilt which was well regarded in the online community turned out to have a giant shady pyramid scheme going on behind the scenes, and a lot of people got screwed back in 2011 when Black Friday happened.
Online gaming really is like the wild west man so tread carefully. If after all this you still find you must gamble, do yourself a favor and go to a real life brick and mortar casino to hit the blackjack table. At least then you can be guaranteed you are getting a fair shake even though you will probably still end up losing.