Newbies can't start their bitcoin trades on here with paypal, gotta use irreversible methods if you're buying. You could look legit and do $10,000 of transaction in a couple months, and then walk into the bank and reverse them all.
This will, of course, get you banned from PayPal, and probably your bank too if it's any significant amount of money, so there's a limit to how many times someone can pull this scam. I worry much more about stolen paypal accounts.