Check the dates. Walker ended in 2001. Dodgeball was mostly produced in 2003, and he's barely in it. The memes started up in 2005. The political stuff was 2007. Expendables was 2012, and he's barely in it. It's a pretty big gap of time. But it's hard to say someone's career nosedived when they actually just stopped making anything. It was more of a soft retirement. He's an old guy. He could have easily made a movie or something if he actually wanted more money/notoriety. He didn't make any money over any political comments as there would be no way for him to monetize that. If anything, he probably lost notoriety/popularity over that, which is something he had to have known would happen before doing it.
At the time, I did wonder if he was angling for running for office himself, but it now seems he has no interest in that.