Let me explain it another way: The Democrat's impeachment was a reaction to President Trump's exposing Joe Biden's corruption. President Trump knew what he was doing, and he knew of the risk involved.
Had he not brought Biden's corruption to the foreground and made so many uninformed Democrats aware of it, Joe Biden would be the Democrat's top candidate today.
The fact that Biden had dropped so far in the polling is an indication that Democrats are now aware of how bad a candidate Biden really is.
And the best part? President Trump pretty much took him out of the race without even having to wait for the election.