>What makes even less sense is wanting use to use software like vSphere or ESXi since its about 10x more complicated than just using virt-manager/QEMU.
I always just assumed it was as a learning experience. When I was in my 20s, I didn't try to get Apache, qmail, and bind running because it was practical for me, I wanted a marketable skill. There are lucrative jobs out there for people who know these technologies.
That was my experience as well. Home labs seem to be cyclical for a lot people including myself. Started with a big overkill rack to learn technologies, and now I’m down to a 10 inch desk rack that is ATX case size with just a few things to run my network and small VMs.
The application side is a more understandable. There are lots of reasons to know and use apache, postfix, etc.
As far as learning goes, if you really want to work in enterprise IT then vSphere is good to know but if you are willing to learn things on your own then you might as well learn kubernetes, docker, etc.
Knowing things like vSphere is cool & perhaps useful but it also hides the how things work. If you want to know and understand things it is better to stick to the open source & interact directly with KVM and Xen. Like you wouldn't use cPanel to learn how a LAMP stack works.
What if you just want to spin up servers in an easy to use platform so you can use them to other things, and not learn the integrals of virtualization?
Then KVM is still probably the move. Install Ubuntu, then install Cockpit for a web interface to manage KVM and Docker. If you want a little more depth, Proxmox is also good but there’s some mild learning curve there.
Best to avoid vSphere/ESXi in that case. I learned using qemu and was able to step into many roles immediately, including some VMware ones. The Linux/qemu/Xen ones pay better.
I always just assumed it was as a learning experience. When I was in my 20s, I didn't try to get Apache, qmail, and bind running because it was practical for me, I wanted a marketable skill. There are lucrative jobs out there for people who know these technologies.