You should read his "Manifesto." Kaczynski was a highly intelligent but asocial wretch who couldn't get laid, so he used his intellect to create an elaborately argued worldview to cast the blame for his misery, not on himself, but society at large. That worldview was so convincing that he not only fooled himself, but many other intelligent people who really, really, ought to know better.
Incidentally, as an aside, I have personally had the honor of being called a "kook" by the Unabomber, in one of his many correspondences.
“They took the poor man’s typewriter?”
He’s anti-technology, remember?