[delluminatus]

I'm guessing you were thinking mostly about financial and political self-interest (the things we usually classify as "greed") when you wrote this post. But I think there are other, equally important ways to be selfish.

For example, humans evolved to be social creatures. Interactions with other humans impact our body chemistry in dramatic ways. I want to avoid loneliness, so I selfishly hold relationships with others. I want to hear people say "thanks" to me, so I selfishly give people gifts. I want to be able to be righteous without hypocrisy, so I selfishly stick to my principles.

Just my two cents. There are a lot of different types of desire in the world. Who's to say that UBI wouldn't be in folks' best self-interest?