From USD2000 dropped down to USD1400 for only 2 days?
Anyone knows what is happened?

The cause is for the reduction of bitcoin price.When the price of bitcoin had increased to high value,you can able to see good rise in the price of Ethereum also.But you should need of patience.Keep buying Ethereum at all low price.You may get shocked at one time,the returns you are getting from the investments.It will make you happy at some moment.
Agreed with you the whole market was overheated and it need a healthy pullback to keep continue growing. Even it is terrible experience for some people who entered at peak price but that is clear ETH has great future and it would be nice to stay clam and keep trust in it.