Gambling has only issues with it. Advantage is just having fun. Eventually , the issue is you loose everything.
In many cases (if not in most cases) yes, you lose everything in the end. But when this "everything" is just your balance which is less than 0.5% of your monthly income then it's not a big problem. It is still fun even though you lost "everything".
That's the key really, you touched on a very important aspect that is bankroll management.
If you do that well, you will hardly have any problems with gambling, and if you can have fun from it, which is normally possible because of the thrill it brings, you can call that an advantage from gambling.
Also I don't really agree that you will always lose everything. There are many players that have proved that you can profit from gambling if you are skilled enough (at least in poker, sports betting and trading)