Here in North America we have a lot of stuff. Mainly we have a lot of energy (not the "let's play go to the park and play Ultimate!" kind, but the "turn up the heat, Martha, I don't want to put on a shirt" kind), and we have a lot of food. And when people have access to a lot of something which is required for survival, like food, or which makes life easier, like energy, we consume as much of it as possible. It's our nature. We evolved in an environment where calories were scarce and precious and anyone who didn't leap on food (more calories in), or seize the opportunity to do less work (fewer calories out) was a fool. A dead, extinct fool.
There's an article in the 11 November 2010 New Scientist which says that 40% of the US population will be obese by 2050. Oh, that's terrible, those disgusting Americans. But Americans are just like everyone else, except they are constantly surrounded by huge quantities of cheap, high-calorie food. And so they eat it and they get fat, just as we all evolved to do.
At the same time energy is cheap and abundant; there are labour-saving devices for almost every task imaginable, from changing the channel on your TV to raising your blinds to feeding the cat, to say nothing of that ultimate calorie-intake-optimizing innovation: processed food. And we avail ourselves of every one — there are precious few people who will say no to a labour-saving device on principle, and most of them are so cheaply run we add them to our lives without qualms. No-one ever rejected an automatic can opener on the grounds that it would cost too much to run.
The only way to control this process is legislation — by making overconsumption so much more expensive than austerity that austerity begins to look good. We need enforced privation.
Show me a politician who will run on that platform and I will show you a politician with a very short career indeed.
So to conclude, we're screwed. The only way off this rollercoaster of plenty is to run out. Run out of oil, run out of soil. And then lots of people will die (hopefully none of my descendants) and maybe enough of us will survive (and the planet will be habitable, because of course there's enough fossil fuel left to ruin the place completely if we burn it fast enough) to start the whole merry-go-round again.