Yes i always buy when the price drops sharply.but it depends on the coin whether it is worth to invest in or not. i will buy because this is a good opportunity to get a profit. It takes a long teme but it is an efficient way to make so don't miss such a good moment.
I think that bitcoin price will not down more than $6000 because if it happens that will be the end of bitcoin. With low price it will get buyers but there will be no supply of bitcoin. Miners will not mine bitcoin because the mining expenses will never allow them to mine bitcoin otherwise they will lose their money and waste their time, because of no profit at all.