(2) and there is nobody left in the world who would be hurt by your death (no close friends or family)

That's actually an extremely strong precondition. People in modern society play positive-sum games all the time; in most interactions where people exchange one good or service for another (such as in selling their time or buying a material object for money), that leaves both participants better off.

A productive member of society killing themselves - even if they have no friends and are unlikely to make any - leaves the average surviving member of that society worse off. Many unproductive members of society (politicians come to mind) could probably become productive if they really wanted to; throwing your life away in some branches is still a waste.

None of this applies if you're a perfect egoist, of course.