Coin theft is down to bad management, the manipulation is pretty bad at this stage, not much can be done to disrupt the market because it's so big and widely distributed. Mostly people trading in bitcoin are looking to just transact in bitcoin and redeem that value in dollars or other fiat currency pretty much immediately after the transaction which means the value gained is closed to what the value traded is at.
Also bitcoin in some senses might be considered an investment if you anticipate the market to go up in future, which it has historically done on and off.