Trump lost because of 3 reasons, In no particualr Order
1. Corona …People did not think he really cared about it.
2. Personal Behavior / Tweeting . People didnt really like his personal behavior, the insuilts, the tweets
3. Mail Voting There was no fraud with Mail voting, but mail voting is easier than in person voting, It takes 5 mins and you dont have to stand on line to vote for hours. Trump claimed this was a fraud instead of telling his supporters to mail in vote, The dems encouraged people to vote by mail and these were banked votes