A lot of the stupid, illegal, and dangerous shit that Tramp and his cronies have done can be quickly reversed by the new administration.
Other things are more difficult like the stacking of the Supreme Court (which must be changed to eliminate lifetime appointments).
The biggest problem are the 75 millions people out there who voted for him. Not all, but most of whom are racists, misogynists, homophobic, and just plain idiots. And plenty of them are elected officials at all levels of government.
Social media has proven to have much more potential for harm than good. But that genie is out of the bottle and may prove to be the most dangerous challenge that there is to the future of democracy.