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.
Perhaps you should google "open source" my friend.
...That's okay... you seem to be kinda new to this open source concept. We'll give you some slack.