https://en.m.wikipedia.org/wiki/Post-election_lawsuits_relat...62 lawsuits in 9 states, 30 dismissed on merits, several from Trump appointed judges.
My recollection is that when the cases went to court, the lawyers backed away from claims of fraud: https://time.com/5914377/donald-trump-no-evidence-fraud/
Trump was consistently losing in all polls in 2020.
538 had Trump’s odds at 10%: https://projects.fivethirtyeight.com/2020-election-forecast/
Betting markets had him at ~35%: https://www.realclearpolitics.com/elections/betting_odds/202...
Biden was favored in MI, WI, NV, PA, AZ, FL, NC and GA on Election Day meaning he had many paths to victory.
And polls were pretty accurate for Biden:
State - Polling Avg. (Result)
MI - 51.2% (50.6%)
WI - 52.1% (49.5%)
NV - 49.7% (50.1%)
PA - 50.2% (49.9%)
AZ - 48.7% (49.4%)
FL - 49.1% (47.9%)
NC - 48.9% (48.6%)
GA - 48.5% (49.5%)
The surprise wasn’t that Trump lost in 2020, is was that based on polling averages that he didn’t lose by more.