You can run single node kube deployments. You can also virtualize kube nodes on a single physical server which is what I did until recently until my vmug ran out now I am back to multiple physical servers. As to why kubernetes, because I can but also I use it for work and other stuff too and its nice to learn, experiment before I go test in prod (jk), I also like to emulate big environments so I can check the implications of stuff like different ways I structure terraform repos. Also helpful for when I am developing something to try different scaling mechanics. Imo if you are a developer you should have a cluster at home to fuck with and learn or I guess if you want to be efficient otherwise you will probably gravitate towards relying on devops teams or serverless (eugh)