I'll give you my take, I shouldn't but my life is shit right now so I'm going to anyway. If per OP it's true he got into mushrooms, and I'm assuming this means psychedelic mushrooms and not foraging, then he became the target of a particular section of the secret society that works in the telepathic/paranormal/ethereal realm. The tests conducted during the 60s, 70s and 80s by the three letter agencies didn't just open the door to mind control through psychedelics (this is surface level stuff, easy to brush off). The truth is that there are forces and an entire universe completely beyond our understanding or grasp on a day-to-day, but the contentions in the brain during the psychedelic trip activate parts of the brain that not only interacts with this universe, but communicates to it to. The secret society can detect when an individual is toying with this "other world" a little too much, and snatch them up during the process and keep them in a perpetual state of "other". During this period they will conduct experiments to communicate with the other side and further research into their occult practices. It's absolutely a bonus and in fact more than likely by design that this guy was well-off and intelligent, because the other side can talk through him in a more coherent and streamlined manner (i.e. he isn't possessed). Which is why they don't just pick up any old crackhead. Yes he was controlled, but it's because he naïvely and ignorantly went far too deep down the wrong rabbit hole.