he resales them for a profit. the people who are major players in bitcoin pay premiums for accounts with high posts/trust/activity. people buy these accounts to push their agendas, bump their own posts without looking desperate, troll their competitors and adversaries, and shill bid in their auctions. and yes, i'm sure some have purchased accounts and used them to scam before. good thing is the mods are alerted pretty quickly and the sockpuppet is banned causing the scammer to lose his investment. personally i'm of the school of thought that thinks selling accounts is shady, but in my time here i've come to realize that you must do it to compete with the bfl's and other big business people around here who have 20+ accounts a piece and will stop at nothing to smear your service or product while pimping their own.

r3wt