As US$ are mostly made up fake numbers in FED and other banks computers, FED or other bank could deposit millions of $ to bitfinex (or other margin trading platform) where they margin sell all their fake $.
As they can create and send how much $ they want they can crash BTC price completely. Am I right?
No, you are not. While they can do that, the amount of actual bitcoins is limited no matter how many dollars you print, so people actually buying coins at these cheap prices and moving them out of exchanges will very quickly collapse this scheme, resulting in a blow up of the price to couple more digits.
Even in the theoretical scenario of Infinite $ being thrown at an exchange, it will just collapse at one point as there will be no more BTC to borrow for shorting, and imaginary BTC don't hold well against withdrawals.
What is happening now is very explainable - it happened before every rally, a major shock selloff to throw weaklings from the train and load up on coins; nothing has changed there, just hold on tight.
