I would say that actions that make a particular person happy can have consequences that decrease the collective happiness of some group. I might use a tyrant or an addict as examples. In answering the question "What else are you gonna do?" I'd propose at least "As long as you harm no group happiness, do what makes you happy," the Wiccan Rede "An' ye harm none, do what thou wilt" probably being too strict (rules out being Batman, for example).