You seem to also be implying that by running a single bare metal server you have eliminated any chance of downtime which isn’t true
For example if your process crashes on bare metal, you go down, unless you have some kind of supervisor that watched and restarts the process, if youre not using kubernetes as a supervisor then you need to set one up using some other tool. At the end of the day you can’t eliminate all tooling/downtime.
If a single server fails, you may be offline but there are well-tread paths to come back online. Your material cost is the cost of that single server. If k8s goes down, oh boy. Not only is it very complex, requiring knowledge of how it works to diagnose and recover from, but there can be zero documentation on how to recover. You are now also paying for a cloud of bricks.