People do this on their own time because they enjoy it! Why is this so hard to understand.

It's the same reason why people like woodworking. Why buy a piece of furniture when you could spend 3x as much and do it yourself?

We can call it a workshop instead, since it’s more physical. I associate lab with a place you do lots of thinking.

Why not? They might use it to experiment with different techniques to bend wood, test structural integrity of different joint types, well anything.

That's why you buy the last generation of common enterprise components used when industries mass upgrade, which happens every few years.

I built mine in 2018 and I paid $65 each for two E5 2670 v3 ($1600 MSRP, 2014 CPU), and $300 for a dual socket motherboard with 128GB of ram. Yeah it's not the latest and greatest but it's been going strong since then.

That's awesome. Reminds me of retro computer enthusiasm. It's not about the hardware, it's about the experience and keeping classic tech alive.

Yeah, it's cheap and the hardware is still enterprise level hardware so it's more than capable of handling personal lab workloads (esxi and proxmox still fully support my hardware) and it's been very valuable for me to learn how to stand up and manage similar environments, which is not something I usually would be expected to do in my profession, but has been great for supplemental skills in my career.

Who the hell do you think you are judging people's interests and hobbies?

I could say the exact same thing about however you decide to spend your weekends.

"you're more than likely unfulfilled in your current career"

Thats quite a lot of people, personally i would rather be planting trees, it i could pay the bill with that