What defines success is obviously a longer discussion. Certainly, it's not all about money.
I'll keep it real simple, let's just say not being a fuck-up is success for this discussion. (i.e., keeping a marriage together, not committing crimes, setting the right example so your kids don't have kids before they are married, etc.)
Your friend is a student and it's great that he's doing well. But, once he moves on to the next phase of life (with perhaps a wife, kids and more professional job), would he still continue his regular use you think?