I know you are far more acquainted with American culture than than I am of antipodean culture, but I'm going to reply as if you're a tabula rasa.
The embrace of conspiracy by the right has a long history in America. There was the Red scare back in the 50s, not entirely unwarranted but certainly encouraged a certain amount of paranoia. In the sixties the John Birtch Society came along and that was pretty much the same thing, but a little less mainstream.
By the seventies we have the dawning of Evangelical Christian conspiracy theory, and I think the Genesis of that (no pun intended) was Late Great Planet Earth. Eschatology and politics became more intertwined in the Evangelical mind causing them to look for patterns and signs that were typical of a conspiracy theorist. By the '80s and '90s you had Jack Van Impe, The Prophecy Club, Creationists like Hovind and Ham who didn't merely think evolution and deep time were wrong, but an orchestrated attack on Christianity, the Left Behind series. There was also the Satanic Panic.
The 90s also so the right begin to engage in secular, political conspiracy mongering. The Clinton's were running a drug and murder operation out of Mena, Arkansas. Hilary had Vince Foster murdered for (reasons). The New World Order was going to send United Nations troops in to take our guns and enslave us.
35 years of that from the Conservisphere and I can see why right is much mote likely to think a cabal of elites, most of whom are literally demonic, want to take their guns, send them to reeducation camps, and execute them if they won't take the depopulation vaccine so the earth can be reduced to a population of 500 million.
