And it's not what they do until it is. Amazon is making some decent movies and series.
It also requires taste and vision, two things that Kanye West utterly lacks.
Popularity and quality are orthogonal.
Kanye's music, particularly from before the last few years, has been well reviewed by critics. His shoes were popular among "sneaker heads", or people for whom sneakers are a hobby.
I'm not saying that they are bad, just that they aren't at the same level as brands like bose and sennheiser which are way less focused on celebrities branding.
Anyway, the point still stands, Beats is considered a fashion brand, it was used by athletes all around the world a couple years ago, now athletes are all in on apple airpods and it's been a while since I've seen someone talking about buying a beats.