You're not joking. If you're like most people and have only a few TiB of data in total, self hosting on a NAS or spare PC is very viable. There are even products for non-technical people to set this up (e.g. software bundled with a NAS). The main barrier is having an ISP with a sufficient level of service.
But if you have a lot of data, self hosting is still cheaper.
Its always gonna be cheaper because you don't have the cloud provider's profit margin, which can be quite high.
Sure, hardware is cheap.
However if you actually follow the 3-2-1 rule with your backups, then you need to include a piece of real estate in your calculation as well, which ain’t cheap.