Nobody dogmatically believes in this. This is not an "ideology", just some people having fun speculating existence. A far cry from religion and conspiracy nuts. Stop being so grumpy!
People in crisis are finding their existential grounding in these emerging belief systems about "the simulation" and other scifi-inspired ideas, are taking them exactly as seriously as novel belief systems from other eras, and are assembling into communities that collectively reinforce their beliefs.
I don't think you can really prevent that from happening, as we see it throughout history and geography, sometimes just forthing in small communities over a generation or two and sometimes sweeping across a whole societies in a profound way, but its ultimately common for "speculating existence" to be both casual parlour talk for some people and an emerging dogmatic belief for others. And that's exactly where we're at with this stuff now.
I suppose neither you nor GP claim that most people have this "slot for magical thinking" but I find these properties of the religious thinking that I list above can be fulfilled by perspectives that aren't necessarily magical. And I dare say, such perspectives have supplanted them in general. I guess I'm replying to the adage "everyone has some religion." My reply being, "are you sure that's a religion?". Forgive the hazy brain rant.
Paperclip maximizers may never come to be but what do you know, smart machines may upend the world order in Bostrom's lifetime. I'm not very familiar with his work and the amount of rigour that went to it but I generally expect we'll regret some of the consequences of this technology.