Many Americans are sickened by the destructiveness of the Trump administration. The obvious solution is to vote him out, but not everyone agrees with that. There are some voters who are just as repulsed by Trump as the rest of us, yet they don’t plan to vote for Joe Biden either.
In a perfect world, we could all vote for a perfect candidate, and that perfect candidate would have a significant chance of winning, with or without being on the ballot. However, we do not live in a perfect world. Why can’t the idealistic 3rd-party voters and write-in voters understand that?