Ask HN: Friend's 15 year old wants to drop out, I've been asked to intervene

After reading the letter he wrote to his principal (included below because HN won't allow an Ask HN post over 2000 characters) I think I am going to disappoint his parents and recommend that as soon as he gets his GED that he go ahead and drop out.

Any advice / thoughts / concerns / considerations anyone could provide would be greatly appreciated.