Building a cluster is a fun and relatively easy project. You learn much more by having the hardware at your fingertips. You can simulate network failures and power failures or you can crash an important daemon. By causing problems you can see how K8s responds and manages itself when it does not have the nodes it expects. It is important to know these things because, for example, if you create a pod instead of a replica set then the loss of a node will mean the inability to use the pod assigned to that node. You need to know how a pod and a replica set differ in order to create a self-healing stack. You can learn all of that with the cloud solutions but the ability to answer your own questions will always be the superior means of learning.

The Agile movement has convinced many that the solution that gets you up and running today is the best. A good engineer is not afraid of working and learning instead of just buying a pre-baked implementation and calling themself an experienced user. The cluster that I know like the back of my hand is my “real” cluster. The production cluster is someone else’s that I just rent.