First of all I do want to say I'm sympathetic.
But I do want to say, it's not clear from your post whether he had already had anything written before you sent him your statement, or if the draft he sent you is his very first draft. If that is true, I think it's possible that maybe he doesn't feel comfortable in his writing skills, and was literally using your personal statement as a template to base his off of. That doesn't make it okay, but I think there's just the possibility that maybe he wasn't plagiarizing your statement with malicious intent, but because he literally had no ideas for where to start and maybe doesn't have a clear idea of what the PS is supposed to convey or what he wanted to say with his. I also think this might be true because if I was trying to copy someone, I wouldn't email my copied work back to them to edit! lol
Again, like others said it depends on how much you want to keep the friendship. If you think the above is the case I would maybe start off softer, not a full-on confrontation. Just point out that his statement is way too similar to yours and he needs to find his own story (conclusions to make in the statement) and style, otherwise his PS won't sound sincere (okay, yes, who knows if adcoms would really read close enough to tell, but that's probably what I would SAY to him - and also that might show through more in an interview if they were to ask about his PS as it is and he can't talk about it b/c he borrowed so much of it from you). Maybe direct him to some internet examples or a book with PS's so he has more styles/approaches to look at and draw from. You could also have him tell you about his decision to go to med school and you could help him find his own story/structure/conclusions from that story which he could then put in writing. And then if after that he comes back to you with a revision that is still basically your statement after this conversation, then that would maybe would be when I'd confront him more seriously/harshly.
