340 - (74 million children + 70 million Trump voters + 68 million Harris Voters) = 128 million nonvoters, some of who are probably not eligible for one reason or another, so a conservative estimate of 100 million nonvoters
Regardless the worst case estimate from 2018 is 11 million people in the US are fascists. That's a good ball park number to work with anyway. The nonvoters outnumber the fascists almost ten to one.
https://www.vox.com/2018/8/10/17670992/study-white-americans-alt-right-racism-white-nationalists