3 networks?? Where do you live?
I am in Phoenix, been nothing but air tv for a few years now and we get nearly 70 channels when we do a channel search with my 20 year old analog antenna that has been up in my attic since we bought the house. Granted a large percentage of those channels are Spanish language channels, but we watch way more than 3 networks.
BTW, if you have an xbox or even if not, you can download Kodi (the xbox media center program) for your PC and you can watch pretty much any channel that exists though your computer.
But they make their money off cable. Without cable most of them would be gone.