When did he go crazy?

If by crazy you mean enlightened, your answer is "once he took the red pill and started thinking like a man and not a lemming."

"Red pill." Do you people ever listen to yourselves? You sound like a bunch of pre-pubescent idiots.

What did this guy do 4 years ago to trigger so many?

Take a guess?

There have been rumors about dementia for several years now.

Who knows if they're true, but he's still working so if the rumors are true the disease can't be too advanced.

I like him. Particularly in Midnight Cowboy. "Where's that Joe Buck!"

It was either when:

1) Ratso Rizzo died at the back of the greyhound
or
2) Burt Reynolds bust his leg on the rapids....


(Oh yeah...**SPOILERS**)

I believe 1980. Before that he was one of us; then he went to the dark side. Anyway, here's a new interview where he's normal. But you know those ranking and raving ones? Remember he's an actor; the Reptilians give him a script and he reads it with feeling. I don't even think HE believes the crap he says!
https://news.yahoo.com/jon-voight-piece-140801674.html