The cluster that gets handed to me is almost never on fire. It works. It has worked for a year. What has happened instead is that the people who set it up made a series of reasonable decisions under time pressure, wrote none of them down, and left. Now every change is a small act of archaeology, so changes stop happening, and the cluster drifts further from the thing anybody understands.
That shows up in specific ways. Service accounts bound to cluster-admin because narrowing them once broke a deploy at 11pm. Network policy absent entirely, so every pod can reach every other pod and the blast radius of one compromised container is the whole namespace. Resource requests set during the first week by someone guessing, usually at two or three times real usage, which is why the cluster bill grows faster than the traffic. And deploys that work, but only when run by the one person who knows which step to skip.
None of that is a Kubernetes problem. It is an absence of guardrails, and guardrails are buildable in weeks.