Why don't they make an affordable VR headset that uses cartridges?

[x7q3]

With VR being expensive and mostly tied to a powerful desktop/video game console... it makes me wonder...

Why don't they make an affordable VR headset? Wireless, uses cartridges for games, etc. Imagine virtual reality games where you walk on the Moon, walk across a mountain, or explore a huge island.

You just put the game cartridge in the headset, and off you go. No wires, and you can play as long as you like (or until the headset eventually needs charging or something).

What's with the expensive VR average people can't afford? Where's the affordable VR that everyone can easily access?