When I was younger, nonsensical and chaotic was funny and appealing to me. I guess PewDiePie's videos can fit that description, because I had regularly watched his videos around the time I was nearly 14 years old.
I don't think the same videos I watched back then were necessarily funny now, nor do I consider PewDiePie necessarily a good game commentator. What I do keep in mind is that most of his diehard fanbase is around the ages 12 - 14. It might be coincidental, or it might not be.
Try to consider that maybe his videos appeal to a younger audience, and that's why you don't care for his videos. His channel is so popular just because that shade of humor is popular with that age range.
