In a recent essay, Brian Tomasik argues that meme-spreading has higher expected utility than x-risk reduction. His analysis assumes a classical utilitarian ethic, but it may be generalizable to other value systems.

This is particularly the case if you expect those who do manage X-Risk to do so in a way that may adopt some kind of 'average' of human values. ie. It exploits FAI<CEV<Humanity>>. (Probably, by a default interpretation of the incompletely defined outline.)