The FISA warrants seem to have been based on the Steel/HRC paid dossier. It also seems that some of the foreign contacts were set up by CIA operatives ( Papadopoulos, Flynn) to create an avenue to launch the investigative narrative. I do not have enough information to accept that a fraud was not perpetrated on (or maybe, in cooperation with) the FISA court. DECLASSIFICATION would shed light on these questions.
I was giving the FISC , benefit of the doubt. I believe, without evidence to the contrary, the FISC’s decision was intended to authorize an investigation of foreign actors, not a citizen , much less, POTUS.
I believe the crime was how the investigation targeted Trump and other US citizens.