Most Americans look at what Biden is doing, and approve of it. They look at Trump rallies, and realize Trump does not care about his supporters, since some have died, and many have become infected with COVID. It shows in the polling. Trump is actually losing support due to this reckless behavior.
Trump is addicted to being the center of attention, and wants thousands of people to admire him. His supporters health, be damned.
If only Biden can drum up the same support for his rallies, I would even be impressed where he had to restrict the crowds publicly, just no one showing up, more Trump supporters than Biden supporters at his rallies.