Because you're stupid, that's why
I can't tell you how many times I get a private message that says something like
"OMG! I JUST SENT 400 USD TO A GUY WHO RIPPED ME OFF! HELP ME DOCTOR!"
And when I check.. he (the seller) has zero trading history
Well, all i can see is, above the privatemessage is a giant warning about traders with zero history!
NEVER PAY WITH PAYPAL FRIENDS AND FAMILY OPTION!! YOU WILL HAVE NO PROTECTION!
How can I make it more obvious?