If you are a U.S. citizen and don't/won't vote in 2020, then it will be your fault that we wil have to deal with Trump through 2024.
If the options are one neoliberal warmonger vs. another neoliberal warmonger, I can see why people would boycott. I'll still vote no matter what but not for whichever corporatist the DNC decides to nominate. If they want my vote, they must earn it.
The fault does not fall on the voters who find it morally impossible to vote for a Hilary Clintonesque candidate. It falls on the DNC for refusing to nominate a decent leader.