The cost of shiny new tech. "Hey look at all these cool things you could / can do that would lower costs and do other cool things."
Weeks or months later you're still learning about how you do the thing that will maybe lower costs and do cool things ....
Meanwhile the market and mindshare has moved on to the next shiny new tech.
Kubernetes has been here for a while. I'm sure we can agree that it ceased to be a candidate for a meteoric fad for a while now.
I am not a Kubernetes expert but I feel like Kubernetes still has such a high rate of change going on that ... it still is in that phase where you just don't know what you might get out of it... maybe not "just a fad" but still variable enough that who knows where we'll be or if in two years it's all different.
I've probably wasted more than three weeks installing kubernetes on 3 nodes. I've tried Racher, RKE, kube-admin, kubespray and doing everything myself. I always failed and the way it failed was completely opaque and I didn't feel like I could even understand what was going wrong.
Don't install k8s. Use it managed. It's best that way. Too many moving parts for a small op to manage.
Openstack had similar hype (though more on the systems side than the developers), and it seems to finally be fizzling out.