Don't know much about this forum, do ya? 
They buy them to make $$$$, spamming for BTC.
They buy them to make $$$$, spamming for BTC.snip
This is because old users do not give Merit to new users.
snip
Post something worthy of reading. Selling accounts has been going on for a long time, early days it was for pulling scams, now it's to earn BTC.
Seriously, you don't know as much as you think you do, I suggest you read up on the Trust system, why it was implemented, account selling and forum etiquette.