Hello, Instead of posting a new thread, I'll just start here
I work in an industry that requires monitoring cellphone GPS.
The FE argument is that there are enough radio towers to provide accurate triangulation everywhere on the land and ocean.
While there are enough Cellphone towers to provide service to most of the US, there are still cell phone dead zones where GPS still works. Go on a boat outside of 12 NM and see what your service is like, go into the mountains... Please also research E911... There are limitations of radio (cell) towers that satellite GPS do not offer. (Think my sirius satellite radio, or Direct TV)
Instead of putting all my points here, I'll let someone address this first, and then i'll respond with more nuggets of knowledge to further my point that Satellites exist.
As the InFlatEarth would say... FLAT EARTH BUSTED!!! haha