He will soon be penalized with exclusion from the group, noone will want to work with him and show general dislike. That's his problem, the "victims" can only learn to not loan him any money. I assume you are talking about school. In school people often get categorized into a role and it's really hard to get out of that if it happens early. He will be known as the scrooge and that's his punishment. Once your classmates mature it might go away, but the damage to the person could be already done by then so he might change to the worse, learning that noone really likes him. It's a psychological process that happens one way or the other when there is a group (or class) that has a normal functioning hierarchy system in which one doesn't fit.
Though i'd recommend to just confront the person with it, give them a deadline to pay the money back, otherwise shout at him or beat him up. That will probably cause less damage to him and the group structure in the long run.