I tried to read Kaczynski's manifesto once and came away with the impression he was mentally ill. I think there's stuff in there that impresses people with personality types who are disposed to agree with him, and it sounds cogent to those people, but I found it hard to escape that he was pretty incoherent and made logical leaps into a private reality.
I can't recall the details, but I saw a documentary that made me doubt that the mkultra experience was very formative for him. Iirc he had a big change in his outlook and demeanor at around the typical age of onset for schizophrenia and similar issues. According to what I've read, these conditions seemingly have multiple causative factors within an individual, genetic and environmental, where "environmental" factors can include stuff that started in the womb.