We do have at least a hypothetical check on people like Trump, it’s supposed to be the other party. Sadly the DNC is corrupt and pathetic.
In 2016, Hillary and DNC signed an agreement so DNC would get a huge chunk of her campaign money, so they cheated and helped Hillary win the primary system. The exact same thing is happening again and the Biden campaign just signed a similar agreement a few months ago.
The people to blame here when Trump wins again will be DNC idiots again.
Certainly this country could find anyone with a pulse that isn’t 80 years and either senile or crazy.