causing panic selloff to make price dip more... then buy back all the bitcoins you just sold at the new low price like 8 and then he has made potentially millions of dollars and then bought back all the bticoins he originally "stole" from mybitcoin.com users
The problem with this "theory" is: as you say when someone sells it puts downwards presure in the price of bitcoins, but you forget that when someones buys it puts upwards presure.
So if he started buying again at $8 the price would not have stayed there nicely for him to buy all he wants at that price, it would have gone up big time.
This scams dont work unless there is a massive panic selling from other people than the scammer. Otherwise the scammer will loose a lot of money.
If the money from MyBitcoin.com is being sold at the exchanges, most probably whoever is dong it is trying to get out of bitcoins, not buying back.
