"he's sort of a dumb guy"
Well yeah, that's pretty obvious- almost seems like he practically embraces his own stupidity as an endearing quality and/or an excuse to be "open minded" which, as you point out, is a slippery slope when you're as popular as he is. No shortage of notably stupid celebrities out there but I can understand folks being concerned that he's not using his popularity in a responsible way, even if as I said earlier, I mostly feel like he has the right to do what he wants even if I don't agree with it.
"individualist, masculine self-actualization, where you consume lots of supplements to supposedly improve your body chemistry and lots of ideas to improve your mind"
That seems to be an accurate description of the (sub)mentality of Rogan and his fans alright.