Also, the media was running election security fearmongering stories since the day Trump won in 2016. Liberals didn't denounce "Hamilton Electors" very strongly

Also, the media was running election security fearmongering stories since the day Trump won in 2016. Liberals didn't denounce "Hamilton Electors" very strongly in 2016--though, admittedly, Clinton and most democratic leadership didn't support those efforts, and a larger share of congressional republicans supported Trumps attempt at the same thing. The number of democrats who thought the 2016 election result was fraudulent was pretty high. Democratic intelligence committee members outright lied about their evidence for years re Russiagate because it hurt trump. And Democrats were laying groundwork for contested election this time around too. Hillary Clinton essentially suggested Biden never concede if he lost--implying that a loss would equal fraud. None of this is as nearly as bad as Trump is doing. But it certainly helps Trump destroy any norms prohibiting bad behavior.