Utilitarianism

Utilitarianism has a lot of elements to it that often prove attractive to radicals. People interested in egalitarianism criticize utilitarianism for being insufficiently interested in the distribution. The idea that if you just keep giving the same person more and more pleasures, those pleasures will kind of have an inflationary effect - they won't count as much. You get more pleasure out of elevating the experience of someone who is miserable rather than somebody who's already reasonably well off. But you can also make the reverse argument that you might need to have austerity in order to guarantee future luxuries.