Do they need any financial or any crimes? Collusion isn't a crime. They got Cohen to plead to 2 NON-crimes in exchange for him going out and saying Trump is a bad guy. "Read our statement & we will stop persecuting you." They want his tax returns.
They want to destroy Trump and will do so by intimidating & embarrassing any candidate who is endorsed by Trump, anyone who works or wants to work in his administration, anyone who wants to put out a yard sign, bumper sticker or wear any Trump gear.
Or. Isis hostage videos. Same thing.