You shouldn’t have to be “good at managing your finances” in an economically just world. You would have all your basic needs provided for at no cost. Money would only be used to buy things that you want but don’t need. The worst you could do if you were “financially irresponsible” is squandering the money you get for spending on leisure and recreation, on things that don’t fulfill you. No one could go broke because there would be no bills to pay. Oh, and gambling would be banned of course.