> I personally think we're a button click away from going back to the stone age.

One reason to use less oil now is to perhaps preserve it in case we need to 'reboot' civilization in the future in case of a future cataclysm.

We were only able to reach beyond (near-)subsistence living because of cheap energy, first coal and later petroleum. All the easily accessible stuff is now kind of gone, so if there's another collapse (which may be more likely to be global in nature: see pandemics), then depending on how much knowledge we lose it could be hard to get back to the say level without the previously cheap/easy energy.

In past collapses (Europe: Western Roman Empire, Black Death) we were able to eventually recover because we at a simply technological level that could keep going even with the loss of a lot of knowledge.

> I think it's one of the reasons we have to be self sustaining on other heavenly bodies.

I think this will be impossible given advanced countries can't even be self-sufficient on Earth.

Is there oil on those heavenly bodies? Probably no, so you're importing your lubricants and seals/o-rings. Advanced fabs? No? Well you're importing your electronics. What kind of silica is there, because if you don't have the right kind of sand, you're mot making your own solar panels. How much radioactive material (uranium, plutonium, thorium, etc) is around if you want to try nuclear power.