Joe Rogan is fairly well known in specific circles. He's a health buff, known for involvement in UFC mixed martial arts.
He also involved in Fear Factor as well.
Interestingly, he first did stand up comedy back in the late 80s.
Humorously Wesley Snipes challenged him to a cage match, but Snipes backed out.
Rogan really isn't a darling of conservative thought... rather he just refuses to tout dogma.
One of his more infamous moments, was coming out against men, competing as women, in mixed martial arts with the UFC. His reasoning was pretty simple, that he watched a guy, that was bottom rung fighter, get some implants, and claim to be a women, and then end up in the top tier in the women's competition.
In Rogan's own words, said that his skill and abilities had no improved at all, but just that he would go in and man-handle all these woman.
That said, most of his show is comedy, and he has at least 8 million subscribers, and his shows are downloaded 100 million times a month, and he makes roughly $30 Million a year on it.
So, him moving to Spotify is pretty large move.