There's certainly a middle ground between IOT cameras sending a constant stream out to an internet server and a completely private circuit.

First, let's put the NVR inside the network so that we aren't constantly broadcasting to the internet.

Then let's not allow direct access to the cameras from the internet. Instead, we connect to the NVR via a VPN.

You keep control of all the recording and storage infrastructure, and you don't place your trust in these corporations that have been found over and over again to be lying or overstating their security stance.

It's a bad idea because of the de-facto "requirement" that people want everything available everywhere with zero setup, causing cheap, completely insecure solution to become the norm. Just don't use "cloud-based, app-enabled zero-config ultra easy trust me bro I know what I'm doing" camera and get proper stuff that allows you to control what goes where and use decent encryption.