If there is a requirement to have an R or a D beside the name to appear on the ballot that needs to be remedied. Being forced to choose between eating a pile of crap or a bucket of rotting garbage isn't much of a choice.The problem with Trump running as an independent is that there is no guarantee the other GOP candidates would drop out to allow it to happen. If the ballot in each state says Biden v. Desantis, or Haley, it will syphon off votes and cause Trump to lose states.
Many Republican voters will hold their nose and vote Trump even if they don't like him if he's going against Biden. I don't think 100% of those people would write his name in or vote independent if another Republican candidate is on the ballot.
If it's a matter of citizens being incapable of voting for something other than more of the same, well then I guess we get what we deserve.