democrats shot themselves in the foot over vietnam and sirhan sirhan gunned down RFK in a hotel ballroom, helping nixon to the presidency. that guy was as shithead of the highest order. the republican party, despite knowing he was a shithead of the highest order, protected him until it became 100% politically untenable to do so.
then we elected a nice guy as president, but he was too nice, so we went with smiling shithead saint reagan, who really united conservative economic fuckwadery with conservative social fuckwadery. the former broke the social contract wrt the economy by knocking down unions, pushing the burden of taxation further down the income/wealth curve, and eviscerating much of the regulation that had been put in place to protect the public in the prior couple-few decades from the worst of capitalism, while the latter tried to cling to some 1950s whitewashed notion of social structure with the trigger being school integration.
then conservative media really got underway using expertise in psy-ops public relations that the API had been perfecting for decades, even teaching the nazis a thing or two, to gaslight the public against expertise generally, but specifically governmental and scientific expertise, and to push libertopian ideology that essentially meant that there's no consequences for using the public as an open sewer, using the term 'personal responsibility.' that also tied into a backlash against social services - public health, public schooling, welfare, etc. along the way we amped up the drug war, incarcerating (and often disenfranchising) mostly minority men.
bill clinton, who was a bit rapey and a bit of a shithead, tried to embrace 3rd way politics, but that helped cost the democratic party the old blue collar base, while also failing at advancing public health and giving away social services.
then the supreme court decided to halt the counting, al qaeda flew planes into the WTC, shadow president cheney got us into a completely unnecessary land war in asia, and the 'personal responsibility' state allowed banks to become huge systemic risks and crash the economy.
despite that, republicans were out of power for all of about 6 weeks in 2009, during which obamacare passed. meanwhile, kansas billionaires were upset that a company they owned was held (fictitionally) personally responsible for spewing benzene in corpus christi, so astroturfed backlash against the first black president by some of those blue collar whites bill clinton hadn't paid enough attention to into the tea party. thereafter, the republicans got a toehold of power back in the senate in a special election following the death of ted kennedy, took the house in 2010, and started gaslighting the public with phony investigations.
conservative media kept celebrating idiocy and squawking about washington, mitch started refusing to fill judicial appointments (the party of wealth has always known of the power of the judiciary, see the Midnight Judges Act), and the idiots wanted one of their own in the presidency. and one emerged: the birther in chief, donald j. trump. they liked the fact that he appeared to say his mind, despite his mind being full of goo. they liked that he wasn't a career politician. they forgave the fact that he's the ultimate coastal elite, a supposed billionaire real estate developer from manhattan born with a golden spoon in his mouth. even centrist media loved to show him because he was a rating bonanza compared to the rosencrantz and guildenstern of the 10 other completely interchangeable republicans who started running for the presidency in 2015 (or 13, c'mon ted).
combine the idiotic fervor of the 'keep government out of medicare' crowd with the democratic party's choice to run the wife of the man who'd let working class whites get away, the 'but i can't vote for a democrat,' crowd, and the machinations of an electoral system put in place to placate white men who owned black men as their chattel property and and you have the election of a loud mouth idiot who plays up division and embodies all the worst facets of american conservatism since 1948 to the presidency.