writes:

There are currently 5 NOTAMS about GPS for the entire country.

They all reference the same area, but that affected area is larger than the
State of Texas, covering some 338,000 square miles at FL400. At 10,000 feet,
the footprint is "only" 120,000 square miles. It covers the entire state of
New Mexico, eastern Texas, most of Arizona, and part of Mexico, plus some
other areas.

Sounds like a real big problem...

See above. Bigger than Texas, and large enough to extend into four different
ARTCCs (whence the multiple NOTAMs).

Since you have never flown a real airplane you probably don't know this
but VOR's fail or are taken down for maintenance all the time.

I don't know of any in the CONUS that have an unduplicated service area of
340,000 square miles. That illustrates part of the problem with satellite
navigation systems.