Tinfoil attention seeker or big claims/flimsy evidence pleader. There's also a lot of lonely, sad people who say the FBI's watching them and have a file on them... delusions of grandeur.
Not that that's proving anything but it gives me a harder time to entirely dismiss it.
The Joe Rogan interview linked in sibling comment is an interesting follow up to the initial interviews with George Knapp from the late 80s.
Just make an international phone call with a non-citizen, for the most obvious example. Slightly less obvious is just walking around outside if you are within 20 miles of a big city or an international border.
To me, that I still look at these guys claims of spooks watching them with incredulity is a bit disturbing. They were obviously nuts, but now it's a fact of life? Totally bizarre.