At least under Reagan, many of these policies had never been tested.
Republicans of today are several orders of magnitude worse. We've now witnessed the damage of trickle-down economics, of vilifying "pinko commies", of ignoring a global pandemic... And yet they do it anyway.
It may be tempting to think that, but those policies all had precedent. Trickle-down just used to be called 'Horse-and-sparrow' economics. We had red scares before, and each of them were just as stupid, if not moreso (the one time we actually should have been wary, in the early-mid 40s, we were blithely complacent - go figure). And prior influenza epidemics and the spread of longer-term diseases had shown the danger of taking a lackadaisical approach to public health.
Reagan wasn't the birth of these policies - he was just the one most successful in lodging them long-term into the rotting craw of American politics.