The Libertarian Party used to be a bunch of dissatisfied hippies. WTF happened? It all seemed to go down the toilet around the time of the Ron Paul moneybomb thing.
Republicans who weren't happy with Trump co-opted the Libertarian movement and started identifying as Libertarian without actually changing their values or beliefs.
Libertarianism had an active conservative population long before Trump was around. They're the "taxes are theft and government gets in the way of the free market" conservatives dialed to 11
In much the same way that cemeteries have an active population of dead people. The Venn diagram of Libertarians and right-wing assholes is largely just a circle.
Ron Paul and his racist newsletter were a thing in Libertarian circles at least 15 years before the "it's happening" meme. I had a Libertarian roommate in the early '90s whose only gripe with Reagan was that he expanded government too much. And of course the Libertarian Party was started by those noted socialists the Koch brothers.
I'm not really sure where the pining for past glory on the part of American libertarians comes from. Seems like this is another case where the American definition of a term has crowded out the European definition that many might prefer.