Years of carefully curated anti-intellectualism in every bit of media they consume, because facts didn’t suit the wealthy (smoking is bad for you, fossil fuels are destroying the planet, private prisons drive more recidivism are facts that get in the way of someone making lots of money). Those fighting facts that aren’t on their side have embraced a number of other groups with anti-intellectual elements (white supremecists / neo-nazis / anti-woke, religious, anti-vaxxers, natural health advocates) to create alliances of anti-intellectual thought.

This has driven increasing polarisation in the US; 49% of republicans approved of JFK as president, and 49% of democrats approved of Eisenhower. It went down over time - other party approval was 30% of Carter, 31% of Reagan. There was a break in the pattern (44% for Bush Senior), but back on track to 27% for Clinton, 23% for Bush, 13% for Obama, 7% for Trump (first round), and 6% for Biden. So in other words, Americans are so polarised that they’ll vote for whoever their side puts up, and for one side, being anti-intellectual is actually seen as a strength.

I think many of the people who started the anti-intellectualism ball rolling on purpose are wealthy neoliberals who believe in laissez-faire free trade as a fundamental value, and so there is a certain aspect of ‘leopards ate my face’ to this leading to the anti-intellectualism extending back to rejection of mainstream economics (even though the neoliberals’ preferred theory is notoriously flawed, Trump’s approach to pulling economic levers is wholesale rejection of all theory rather than replacing it with something less flawed).

Election fraud.

The American electorate is mind-blowingly stupid.