Idk plumbers, electricians, contractors, etc make a lot around here. I’m sure they usually have business overhead that factors into their hourly rates (like $100+ an hour here in Seattle). Or if they work independently, they’d still need to pay taxes, insurance, health insurance, licensing, etc., but assuming they make $60/hr after all that, that’s pretty good.
I built a Ryzen 5800X machine using a cheap AsRock motherboard and three 8tb WD Red drives for about $600 USD. I did reuse the case, power supply, and NVME cache drive from an old build. I’m running Unraid and it has been great!