If there is truly “no collusion,” then why is Trump and nearly everyone in his rotten administration doing everything they can do squash the investigation? If you did no wrong, why not let it play out? If it shows you to be innocent that’d be a HUGE f-you to your critics who’ve been pushing the Russian collusion stuff so hard.
Maybe there was no collusion, but it’s obvious there’s something they’re scared about and don’t want anyone to find out.
Trump (and his family and companies) have been dealing with a lot of shady money from Russia and elsewhere since his last financial collapse around 15 years ago, after which no one (with the exception of the 'shady for a major bank' Deutchbank, who he already owed a lot of money) would deal with him. The idea that all of his dealings in the last 20 years have been non-criminal stretches credulity to the breaking point.
On the other hand, it's possible the he's just been overreacting because his real net worth is negative, and his ego can't stand the idea of anyone finding out.