It's just what the other people said. Basically, imagine a podcast like Joe Rogan, except not insane lol

He's the everyman giving his two cents on current events in a non-pretentious, non-SEO optimized-for-engagement way. (There's even a meme about how generic all his video titles are, "X situation is crazy")

The reason he's popular is the polar opposite of slop like Mr. Beast. He isn't trying to maximize viewership with stupid bullshit like "I SPENT 20 NIGHTS IN 20 MANSIONS!1!!" It's mundane commentary that most people find relatable, the most part being key. He's popular because the median average of viewers find his content agreeable and are one of the first sources they reference for pop culture or weird topical news "I wonder what Charlie's take is on this".

Check out one of his videos about a topic you find remotely interesting, maybe it'll make more sense.