Hogan is a famous, well-liked millionaire[0] already. And he almost certainly doesn't like Gawker.
So maybe he thought, "I can give up some of these millions and these parasites will not publish another damned lie again". In return, he also gets the eternal gratitude of people who hate Gawker (all decent human beings).
Seems like his actions align quite well with his interests.
Your own link says he is no longer a millionaire. He changed from financial motivations to moral superiority after the investment of someone who wants to destroy Gawker (not that Hogan might not also want that)... reducing your ability to receive damages doesn't seem to align to me as well as it does to you.
Me, I'd take that cut.
As Thiel himself said, "even someone like Terry Bollea who is a millionaire and famous and a successful person didn’t quite have the resources to do this alone."
Thiel also said that, but for his involvement the plaintiffs would have accepted a pittance. The outcome is largely a consequence of an the intervention of an outside party, not merely the merits of the case itself.
I think it's a moot point, since both Thiel and Denton have enough money that throwing more money at lawyers would do practically no good. Yes, people with more resources win more lawsuits, but there are diminishing returns.
That money's not gonna conjure up evidence from the luminiferous aether.