Him winning, and getting the votes he did, had nothing to do with people wanting to hear him speak or him being the most popular. Trump just wore out his welcome so bad that any of the fence sitters and those who typically don’t vote, voted for Biden. Also, since it seems left leaning folks typically have been avoiding the crowds/rallies etc during the pandemic, they’re probably not going to go out still because they’re scared. Either way, Biden does not “move” folks the way Trump did with his speaking, which is another reason for the poor attendance. No mass conspiracy.