I was comparing the payment to buying or operating a server (even a free old server has costs, e.g. for electricity). In truth, a proper modern comparison should be to a free plan from one of the cloud providers which is likely to be 0/month.
Sure, but if the machine is already running, it's free. Or if you can stick it in a cupboard at work/university, it's free.
> 0/month
is there actually free cloud hosting? don't they ask for your credit card first before they offer you "credits"?
It still has costs for admin and electricity (via extra CPU load), though I grant these could be marginal.
>Or if you can stick it in a cupboard at work/university, it's free.
This is using someone else's resources, rather dubiously ethical. I suspect IT is going to have a fit when they find out - assuming they didn't block the relevant ports in the first place.
>is there actually free cloud hosting? don't they ask for your credit card first before they offer you "credits"?
There are free plans on Azure/AWS/GCP. Asking for credit card data does not mean you are being charged, I suspect it's really more about identifying users.
It's possible to set up free plans without credit card if one has some other id (e.g. Azure's free plans via MSDN). A prepaid card should work as well.
You could run it in a VM, which is equivalent to what your 20$ host is doing. Or you could run it on a separate machine. Or you can run it on the same machine which was common back in the day... if you use a reputable distro and apply updates regularly then it's really not a concern (i can't remember myself or anyone i know hacked through vulnerable packages, except for Worpress but that's precisely because it's not packaged by Debian).
> 20$ a month doesn't sound too bad
Doesn't it? I guess it's a matter of age and class and nationality. If you're too young to earn money, it's a barrier. If you're in the lower classes of your country, 20$/month can be a lot (that's like food for 30 days for one person). If you're in a "poor" country (i.e. neo-colony depleted of its resources by global north countries), 20$/month can even be considered a decent monthly income.
> buying a separate server
That's the thing. You usually don't have to buy it. It's old hardware lying around or that someone will donate for the purpose of running fun projects.