If bitcoin price drop to 1$,it must be any reason behind that. like technical problems, attacked on encryption system... etc.so its still risky to buy high amount. but still i will buy 500$ btc for future price increasing.because one day btc system will alive soon again in such types of Case.
that's nice reason, maybe someone will find a biggest bug in bitcoin, then he can decrypt the private key just wait see his bitcoin. so in this case exchanger will close his service. i think if this case come to bitcoin, no people interesting to expose his bitcoin address and no people interesting to buy bitcoin.