A beaker full of death wrote:
Shatner owned a small percentage (5%?) of TOS
That said, he only learned late in life that he had to pander to the Trekies to make them like him, so he did a George Forman and started making fun of himself. He went from a serious actor who took his craft seriously - yes, perhaps too seriously - to a clown.
Personally, I think we may have missed out on getting some great performances out of him.
I have a little problem with this narrative. Shatner's not a clown. Any self-effacement we see is genuine enough to make it touching (IMHO of course). His cover of "Common People", and that whole damn album, is utterly brilliant.
I think at some point after doing fare like "The People", "Horror at 37,000 Feet" (Not the TZ ep), and "The Devil's Rain"...he became unable to convince himself that the guy who did some marvelously subtle work in the first season of TOS, and his first TZ appearance could do that again.
The fact that he could reinvent himself as someone who still has something interesting to say on the human condition is nothing short of amazing to me.