Because Bitcoins @ $5 is the same as Bitcoins @ $10,000?
You don't seriously think that were bitcoin to be successful, the Internet trolls posting a message would have the same effect as that same message would have now?
You're correct there is risk trading with Bitcoin right now; but as the market grows that risk reduces. As the risk reduces it becomes a more attractive currency. It remains to be seen of course, but "never legit" is just hyperbole.