Wouldn't it be easier to build an open hardware/source alternative to Ring cameras.

Why would someone buy one? It would be three times as expensive, harder to set up, and require a self-hosted video server.

The point is there are already many millions of Ring cameras installed. Most people aren't just going to rip them out for open source ones.

The other home security camera companies already make cameras in a doorbell form factor.

Point is to do what you want with the hardware you supposedly "own".

Design and manufacture open hardware for 25k?