i for one liked the ending for that exact reason

Mist everywhere, monsters big as buildings roaming around, as well as small dangerous ones; Car is dead; No immediate supplies; You've seen what those things can do and how they can make you suffer before you die; No foreseeable hope that any human forces can help you. Got a gun that can end It all with no suffering.

The bitter aftertaste, when the dispair takes place is, chefs kiss. Not every story needs a happy ending.