I see that price dropped from 1000$ to 150$, why?
sell more than buy?
Also a small volume for such a big coin..

because sellers can't find a buyers at this price and are not yet ready to sell at the lower price
or buyers can't find a sellers at this price and are not yet ready to buy at the higher price
or all who wanted to sell have already sold, and all who wanted to buy already bought
such a big coin.
not really big, there only 15btc in buy orders. If you have 100 btc in this coin, unlikely you will get even 1/2 after the dump. Very little coin, not big