You can lose a lot with gambling but it also depends on what kind if game you are playing online.
The fact is also that losing with gambling is normal and you can lose everything you are owning with gambling, look at the addicted people.
You can lose all your money with gambling if you don't know when to stop, all the gambling games are risky, any game with chance to double, triple money fast, without effort is very risky and can lead you to bankruptcy.
I agree losing in gambling is normal, that is why it's better to don't play this so much.