The first live k8s cluster upgrade anyone has to do is usually when they think "what the fuck did I get myself in to?"

It's only good for very large scale stuff. And then a lot of the time that is usually well over provisioned and could be done considerably cheaper using almost any other methodology.

The only good part of Kubernetes I have found in the last 4 years of running it in production is that you can deploy any old limping crap to it and it does its best to keep it alive which means you can spend more time writing YAML and upgrading it every 2 minutes.