Far beneath the ship / The world is mourning
They don't realize / He's alive
No one understands
But Major Tom sees / "Now the light commands
This is my home / I'm coming home."
Peter Schiling, Major Tom
I found myself waxing poetic after reading this question about the indicator light to tell when Apollo 8 entered the moon's sphere of influence.
When that light came on there was silence – it was a kind of dawning – we were witnessing the first time human beings were falling away from the Earth.
What goes up must come down. It's a law. This is simply how it works. Or worked. In the last century we developed enough technology to go up... and stay up. Someone who enters the moon's sphere of influence can simply choose not to initiate any burn, and wait for their final destination on the moon, never to return to earth again.
But the moon is destined to come home as well:
The Moon will be torn to pieces and every crater, mountain, valley, footprint and flag will be scattered to form a spectacular 23,000-mile-diameter (37,000-kilometer) Saturn-like ring of debris above Earth's equator. The new rings will be short-lived. Theory dictates they'll eventually rain down onto Earth's surface.
So even those who have had the opportunity to spend the rest of their days on the moon (should they have chosen as such) were destined to return, though on a much longer timescale than one might otherwise think.
Of the 533 humans who have been in orbit, have any of them been sent into space with enough propellant to actually escape Earth's grasp, should they have chosen to use the fuel in that manner? Has any human ever had the choice to never return to Earth? (or at least choice not to return with the blessings of ground control, in case there were any missions where the astronauts had the delta-V but not the authority required to use it)