Enough energy for every human individual is already a solved problem, although not necessarily sustainably. It's not even economically prohibitive to switch to

Enough energy for every human individual is already a solved problem, although not necessarily sustainably. It's not even economically prohibitive to switch to sustainable options, there's just insufficient incentives at this time. The great travesty is that, when incentives are put in place, the Holocene damage will be difficult to stop and impossible to reverse. Our own survival chances seem to be a fraction not close to unity, but not close to 0 either. Give it 75% to be optimistic. After that, robotic seed space ships could be a buffer to protect from subsequent cataclysms. That does nothing to answer the questions of Fermi's paradox, unless you low-ball to 1.0e-6% chance of survival. Doomsayers guessing such a number are not generally taken seriously. Looking elsewhere, we have almost unlimited wiggle room in the chance of photosynthesis evolving. Traits that evolved multiple times in Earth's history are inadmissible to this discussion, but several critical traits evolved only once. Fertile but desolate planets are, based on current science, probably abundant. As a typical reasonable human, this is a perfectly sufficient speculative answer.