4 separate Republican appointed judges independently agreed with the warrant and disagreed with you.
This article from a former FBI Counter Intelligence Agent who completed FISA applications explains the process. She explains the extreme steps FBI took before submitting the FISA application. The FBI took such extreme steps before the application was submitted multiple layers to avoid an application done without merit or worse with malicious intent.
https://www.justsecurity.org/38422/aint-easy-fisa-warrant-fbi-agent/