Consider that the US also spends more on healthcare than any other country in the world, as a percentage of GDP.
More =/= better. Something can be horribly overbloated and inefficient and be rather poor compared to what it could be while still being quite expensive and fairly effective compared to everyone else.
Population crises from inability to feed everyone solve themselves, MSH. In a rather horrible manner, perhaps, but they do. And rich countries are unlikely to be the first ones starving.
Also, I'd prefer carbon tax to cap & trade but mebbe that's just me. And mainiac has a definite point; population reduction is an extremely effective way to slow or stop an economy. But it's short term versus long-term losses here, essentially. U.S. is under replacement rate already, however, and it seems really odd to say that the US needs to enact population control when our only real source of growth is immigration, and people are all for that. It literally ends up looking like 'replace the people who are here now with people who could be here later'. Which is...disturbing.
I figure that a natural decline in population will occur after a while and then we'll hit be stable. Similar scale to climate change, too; literally decades and centuries for it to happen.
@mainiac those development experts could be right, but 'widespread poverty will be gone' means something along the lines of 'no longer will entire countries be below the poverty line', it doesn't mean 'no one will ever be poor again!' Post-scarcity society is in the very long works, but it's gonna take a while, and the structures to make sure it works in a fashion we like (nobody starves), rather than one we dislike (almost everyone is irrelevant and ignored, because the few with the skills to be useful don't feel like letting have shit), aren't going to be all that easy.