Unlike before when you go to casino you just bring such amount and after you lose you can go and stop and leave the house, with online access you can top up whenever you and the risk of getting aggressive can lead you to lose everything in your savings.
This is what's happening to most of us. We're there to gamble in the physical casinos but then, if we've got some cash cards or savings card, we tend to use it as well and withdraw money from the ATM and still use those money for us to keep going. It's the same as online but it's more of a hassle when doing it plainly with cash and physical casinos.
It's true as well, though a hassle to withdraw and go back but yup some gamblers really do that in physical casino, instead of quitting they returned with another sets of money that they've withdraw from their savings account and most of the time they lose again, same deal with doing it online but with much quicker and easier process.
Just link your bank or card then request to transfer your money then it will immidiately how up to your wallet and you are ready again to play, though common outcome happens, losing everything then regret with your actions.