But people think that way because of the utility of the hand. Worthless hands are abstracted into the same category (junk) because they all have about the same

But people think that way because of the utility of the hand. Worthless hands are abstracted into the same category (junk) because they all have about the same value. A royal flush, however, has by definition a guaranteed value with no risk involved. You cannot lose with a royal flush, thus the variance is 0, which is the rarest of all things at a poker table.