Sorry, meant to say "end of us", not "end of use".

Here is my attempt to answer your final question about the ultimate point of 'spreading and surviving'. If given the option to push a button that would undo my existence, I would not push it. Would you? I'm glad that I've had the chance to be alive. My assumption is that most people, even some who at some point in their life attempt to end their existence (suicide), wouldn't choose total nonexistence.

We're currently in a very fragile position -- single planet, might not be able to deflect a comet, ect. -- but we're getting smarter and more competent, and the pace of this growth is increasing. Once we spread over a large enough area, the number of future people who will have a chance to be alive goes to near infinity.

Once we're past the bottleneck we're in now everyone can do as they please -- whether that's farming or or industry or whatever -- and take their chances. However, we don't have that luxury. If we choose not to progress now, humans will die out sometime in the near future*, and we'll have deprived all of those infinite number of future people a chance to be alive.

So, yes, I agree with you that the 'better' state will be different for different people. Yes, car commutes and fluorescent office lights and many other parts of modern life are not fun. But we have to do it. It sucks, but we drew the short straw. Sometime in the future we'll reach a place where there is little chance that picking a certain 'better' state of existence that won't mean depriving all of future humanity of the chance to make their own choice.

Anyway, that's my two cents. Hopefully you can now say you have meet someone who has an answer to your question. ;-)

BTW, if you do really want to never see a gasoline-powered piece of equipment again have you thought of joining the Amish? That might work out pretty well.

* Out of context that makes me sound like one of those crazy people on the street wearing a sandwich board. I mean near future as in some finite amount of time that is extremely short in the universal time frame. 5,000 years? 20,000 years? 100,000 years? Who knows, but it will happen if we don't get any smarter than we are now.