Do you plan on keeping it in your home? At that point I'd be worried about ISP networking or power guarantees unless you plan on upgrading to business rates for both. If you mean colo, well, if you're sure you'll be using it in X years, it's worth it, but the flexibility of month-to-month might be preferable.

Because that used desktop is subject to power outages, internet outages, the cleaners unplugging it, etc. Datacenters have redundancy on everything.

Also you still have to pay for the electricity on that thing.

The cloud costs includes everything.

Not to mention physical security.

Breaking into a home is relatively easy.

And unless you live in the US and is willing to actually shot someone (with all the paperwork that entails, as well as physical and legal risks), the fact is that you can't actually stop a burglary.

I'm probably wrong, but this argument always cracks me up.

It used to be called 3 laptops a power scrubber and a backup battery. If you want to go self hosting things. If you were fancy you had two servers.

And you'll need some $100/month to colocate that thing, so you are better spending some more and buying a reasonable server that uses only 1U.