Dims ran a terrible candidate simply because he was so easily manipulated by Obama, Pelosi, etc… He is a puppet. When they could no longer hide his mental deficiency, they kicked him to the curb and replaced him with a babbling idiot. They ran on abortion and “Trump is Hitler, Putin, Xi, and Kim all rolled into one.”
Even with the complicity of the majority of the MSM, enough undecided voters saw through the lies and disinformation to allow an admittedly very flawed candidate to win. They realized they were better off economically when Trump was President.