It's rational to take the certain outcome if gambling causes psychological stress. Notwithstanding that stress is intrinsically unpleasant, it increases your risk of peptic ulcers and stroke, which could easily cancel out the expected gain.
But such psychological stress arises from your perception of reality. If it is caused by an erroneous perception of reality, then the rational thing to do is correct your perception, not take the error for granted. If you are certain that you made the right decision, then you shouldn't feel stressed when you "lose".
It's rational to take the certain outcome if gambling causes psychological stress. Notwithstanding that stress is intrinsically unpleasant, it increases your risk of peptic ulcers and stroke, which could easily cancel out the expected gain.