Every human on Earth vanishes, except for one random person in the US. A button is placed on the summit of Mount Everest that can be pressed to undo this change. Can humanity be restored?

[u/ThePriestofVaranasi]

Every human on Earth vanishes without a trace, except for one random survivor: Ethan from the United States. Moments after the disappearance, a mysterious device materializes before him, displaying a message:
"Humanity can be restored. To activate revival, you must press the button housed at the highest point on Earth—the summit of Mount Everest."

Ethan essentially has as much of a prep time as he wants to gather all the essentials like food, water, weapons, vehicles and everything else that has been suddenly abandoned. He can raid supermarkets, libraries, military depots, and pharmacies for supplies. Ethan can still die of old age so this prep time isn't unlimited.

Now, Ethan faces an impossible gauntlet:
He must travel to Nepal and ascend to the summit of Mount Everest without dying.

Can Ethan survive long enough to reach the button and restore humanity?

[u/rexus_mundi]

About 7 years at most, fuel is required to maintain their orbits along with updates from the ground. They will become less effective over time with orbital drift, and degradation of parts

[u/guyblade → u/rexus_mundi]

Shorter than that. The satellites need their ephemeris information updated constantly by the ground, usually every few weeks. I'm not sure if it remains true with the Block III GPS satellites, but I heard the Block II GPS satellites described as "big tape recorders" once: you basically uploaded the timed list of what it was to broadcast and when and it simply dumped that back out. That's not an unreasonable model when most of the complex work--high precision prediction of their orbits--is being done on the ground anyway.