this is so petty. to what extent is he living off of others? he lives in a mangey boat that he paid for. once in a while maybe he gets some medical care (though i doubt it's much because he's young). does every single penny that a person's life costs need to be reckoned and reconciled? do you know how much falls through the cracks for all of us because of frictions? how much you sometimes overpay for your fair share but also how much you underpay? it's insane to begrudge someone this kind of asceticism based on some kind of weird puritanical collectivism - despite what Arthur Jensen would have you believe the world is not yet a business (and neither is life).
I suppose you'd lock him up and .. no, prisoners live off the taxpayer. You'd kick him out of the country so he could make his own way, say, nomadic on a boat with no income? No, you don't like that. Enslave him and take his economic output? Kill him? What are you wanting to do, or wanting to be done to him, in this situation, to satisfy you?