Your life can be snuffed out or horribly twisted in an instant by a metahuman psychotic, an alien dictator, or an extradimensional evil for no good reason at all! You have no place to run, & cannot prevent it.
You can’t fight back, either. The ubers would probably get all pissy about it. (“How dare you try and kill the supervillains! Not passively relying on the gods—er, costumed heros to kind of protect you makes you a bad person!”)
Makes you wonder why all the major DCU cities haven’t become almost uninhabited by now, as the population flees in vain for their lives to the boonies, causing an economic and social collapse. (Probably the same reason that the Godzilla-universe Japan manages to remain a powerful, first-world country in spite of being ravaged by giant invincible monsters every three years.)
Several Elseworlds have presented Superman as a GL or with at least temporary use of a GL ring. No Durlans or Martians, as far as I’m aware.
As for the Daxamite - well, kinda. In an Alan Moore GL story, Abin Sur was taunted with visions of the future downfall of the Corps - the last to fall was the most pwoerful GL of history, a Daxamite, whose name escapes me at the moment.
Oops. I meant to exclude Elseworlds. I know a couple have had Superman (or other powerful characters) becoming GLs. (I like the GL introduced in Another Nail, which I don’t want to spoil, but was the coolest GL EVER.)
Might it have been Lar Gand? Or another member of the Gand family?
When the Key captured the JLA and subjected them to bizarre alternate dreamscapes, Superman envisioned himself as Green Lantern to an unexploded Krypton, who was given his ring by a dying Tomar-Re of Xudar. Oddly enough this delusion happened in real DCU continuity, so this was not an Elseworlds or Imaginary Story.
Considering the certainty that someone in tights and cape will soon come along and offhandedly knock your teeth down your throat in passing while en route to your boss, it would HAVE to be, now, wouldn’t it?