I must admit that every time I hear someone on the left say that Trump is a threat to Democracy I have to wonder if they have even considered what their own party is currently doing, using the courts and the media to try to eliminate their political opposition - - - not exactly the democratic way that things are supposed to work, perhaps these people should look in a mirror before trying to tell us that Trump is the threat
The problem with your theory is that if he did not do anything illegal, he would never have been investigated for wrong doing in the first place.
While all politicians are corrupt in general in some way, most of Trumps issues were from when he was a businessman. I have no doubt that he was corrupt then, as we have seen many ultra rich have some sort of corruption. They have so much money that they feel they don't need to play by the rules. If you do bad shite, you need to pay the piper, whether you're a Dem, Rep, or Independent.