Mathematically is kind of is though. At least that’s how it works out in a FPTP system. A 3rd party/non vote doesn’t carry as much weight as someone voting for Trump, but it still moves the needle in his direction. EDIT: to clarify this, GOP voters are generally the minority, that means the GOP candidate benefits more from a smaller pool of votes than the Democratic candidate does.

If you want to blame someone for Trump getting elected, blame those that voted for him.

I think you can blame both. The Trump voter deserves significantly more though.