I will say this, and I want you all to please understand, this is NOT about the FBI. This is about some very bad actors high up within the circle of influence of the former president, in collusion with his former Secretary of State.
I cannot say for not if Trump is guilty of something. IF he is guilty, I can only suggest that all of this was a method to get the warrant based on intelligence from the CIA or another foreign intelligence agency. As such, they needed an excuse, and used the dossier for this, knowing full well they needed an excuse based on intel from NSA, British.French/Israeli intel or something which they could never reveal so they needed this approach.
That is the only situation I can see this being "legitimate", and if this is the case, I will apologize in the future, as real national security in defense of America always takes precedence if its honest and dire (you can never have a foreign compromised agent as president obviously).
If however, Trump is NOT guilty, than this was all a determined effort to ensure Clinton won, and the Democrats and the globalists controlled America, crushing it from within, via the judiciary and open borders policy.