The invention of breakthrough energy sources are not being blocked by efforts to reduce, reuse, and recycle. They're being blocked by difficult thermodynamics, engineering, and materials problems.

I'm hopeful, but as far as we know it could take many hundreds of years to solve these problems - they might even be practically unsolvable. So it makes sense to also hedge our bets by making the systems we currently depend on more sustainable, rather than just assume we will transcend them on-schedule.