The top answers are good at explaining why he is popular in general. As for why he’a mentioned here: he has the number 1 podcast in the world. So, it’s natural to see him mentioned. His audience also skews male (~70%), and so do the audiences of reddit and HN.

So you would expect to see a fair bit of mentions. Finally, he interviews people from many walks of life, so you can expect an episode to be relevant to a variety of conversations.

So I don’t think he necessarily has an outsized share of the HN/reddit demographic. He’s just damned popular, and easy to mention.