It's actually very easy, because only one person is compiling 'official' bitcoin client which is used by thousands users, force this person to corrupt, backdoor 'official' client and you can destroy bitcoin in just few second... and don't give me argument you 'can Compile it yourself' 90% use standard bitcoin-qt client.
wouldn't surprise me if that is how the prices are manipulated. money=greed
price is falling, you are creating post (useless) about destroying bitcoin and saying that you are not manipulating, right
edit: and btw, it is really easy to check what new parts of code had been changed since last version. Even if most people are using pre compiled versions still someone would raise an alarm on the forums.