If Amash is still getting 1/3rd of the GOP primary vote in this district, it is not beyond the realm of possibility he could translate that to upwards of 5%. The disgruntled ex-GOP Congressman Bob Barr got 0.4% in 2008, enough to deliver North Carolina to Zero that year. Ex-NM Gov. Gary Johnson took 1% in 2012 and 3.27% in 2016 as the Libertarian nominee. That was enough (along with renegade RINO Egg McMuffin, personally recruited by Willard the Rat to try to give Hillary the election) to prevent Trump from winning five states including CO, MN, NV, NH & NM.
Sadly, yes, there are a lot of voters who ARE that stupid. Brainwashed, ignorant, misinformed or delusional, many of whom either know nothing about the candidates or benefit from the corrupt status quo and are happy to watch it all burn down around them. The result of allowing this Republic to turn into a democracy (two wolves and a sheep deciding on what to eat for dinner). Voting should be a privilege, not an automatic right.
The trouble with Libertarians is that they demand 100% agreement with them, and if you do not comply, they will dedicate themselves to helping the Dems attain 50 years of socialism, —just to teach YOU a lesson.