Clinton never had this kind of consistent lead that Biden has had and never came close to averaging 50% in polling averages while Biden has been ~50% since March. Also Trump won because he got all the Gary Johnson voters to defect at the last second (Johnson was polling at 7-8% for much of 2016), there is no big group of 3rd party voters to defect to Trump this time around. Polls had Hillary at 3% in the final tally and she won the popular vote by 2.1%, they weren't that far off.
Clinton never had this kind of consistent lead that Biden has had and never came close to averaging 50% in polling averages while Biden has been ~50% since March. Also Trump won because he got all the Gary Johnson voters to defect at the last second (Johnson was polling at 7-8% for much of 2016), there is no big group of 3rd party voters to defect to Trump this time around. Polls had Hillary at 3% in the final tally and she won the popular vote by 2.1%, they weren't that far off.