Back in my day there was Fallout, where the person you were supposed to be escorting made a mad dash out of the room to freedom and your sidekick, sensing that the mission would be successful, would gun her down.
I am a hapless victim of But I Might Need It Later Syndrome. I can't count the number of games where I arrive at the final boss battle loaded down with a billion super-weapons and curatives which I then scramble to use so they don't go to waste, but invariably I kill the fucker after detonating only three of my 78 galaxy-nuking mega-bombs in his face.