Why being sick is much worse than being hung over...

Well, it's simple really. When your hung over, at worst the residual effects last two days (and by that point, merely an occasional reality lag). When your sick, who the fuck knows - could be a day, could be a week. If you live in a shitty cold place like here, it could take a month to recuperate, much less to prepare for the next round. Come on superhuman immune system!