It's probably some large investors taking profit! They dump at a high price
But as the value goes down, if they wanted they can just buy it back
So definitely not an idiot
with your description then it was an idiot!
because some large investors know very well not to dump and crash the price, they will dump in a way that nobody even notices and usually they place sell orders so that you buy from them. so only an idiot large investor dumps like this.
what happened is the result of all the investors cashing out. there are a lot of things against ether right now which causes this mass exit.
the most important one is the upcoming ICO cash outs.
then there was the failure that happened yesterday in ethereum.
on top of all that there is the switch to POS and the difficulty bomb which will kill ethereum mining and lead to all of the miners leaving it.