(Possibly weak) evidence for this is the underfunding of organizations which actually appear to be trying to save the world (specifically GiveWell's charities and the SIAI).

I'd say that the reason for the underfunding is more the fact that the organizations are rather unknown, not that most people wouldn't prefer saving the world. E.g. when walking to the university I almost daily meet Greenpeace and Amnesty representants harvesting new members but no-one representing SIAI or GiveWell. What are the latter two doing to make themselves more known to the public?