For the next election, you’re either voting for the Democrat or you’re voting for Trump. There is no “third choice.” Any other candidate you waste your vote on helps Trump.
Yes, you want to make a point. Yes, if we got rid of the Electoral College and had ranked voting, your third party choice might have a chance. But for now, we have to play with the rules we are given, and if you waste your vote on a third party candidate, you may as well have given your vote to Trump.
If you want to stop Trump, the best possible way to do it is to vote for the only other candidate who can beat him, and that’s the Democrat. If you are voting 3rd party from either side (even as a Republican protesting Trump), you’re not doing that.
Look at it this way:
When you vote third party instead of Democrat, yes, that’s a vote Trump doesn’t get. But it’s not a vote the Democrat gets.
Here in Pennsylvania in 2016, Trump won by 44,292 votes. 49,941 people here voted for Jill Stein. I’m not saying all of those Stein votes would have gone to Trump, but none of them stopped him.
If a thousand people upset with Trump vote 3rd party as a protest and then the Democrat loses the state by 999 votes to Trump, then what’s the point? Where’s the protest there? What good did that “protest vote” do?
If you’re not doing everything you can to stop Trump, you’re helping him. If you’re not voting for the only possible choice who can beat Trump, then you might as well vote for Trump, because that’s where you’ll end up anyway.