I'm still wondering, why nobody tried to 51%-attack Bitcoin network early on? People were so loyal to BTC network, and others didn't hear about it? Because it seems strange - I know maybe there wasn't many incentive, but when it started in 2010 being traded on Mtgox, it was still only CPU-mineable, and attack was easy to stage as network was miniscule, and it had already some value (0.06-0.1USD/coin but still).
I seem to remember that I read an article discussing 51% attacks, and as far as I remember, their opinion was that they were sufficiently detrimental to the attacker themselves that the author did not consider that they were as big an issue as they first thought.