Why is my 14 year old niece now collecting vinyl? I can guarantee it's not nostalgia. There's obviously more at play there even when acknowledging your point about relative market size.
Many large organisations use Kubernetes (Google, Spotify, IBM, etc). Regardless, large scale and very large scale are different. Kubernetes is well suited for controlling fleets of compute resource in the order of 10,000s CPU cores, and terabytes of memory.
The compute overhead to orchestrate these clusters is well worth the simplicity/standardisation/auto-scaling that comes with Kubernetes. Many people have never had to operate VMs in the hundreds or thousands and do not understand the challenges that come with maintaining varied workloads, alongside capacity planning at that scale.