Quantum immortality and the Fermi paradox.

What if some kind of false vacuum energy exists and is easy to tap for a sufficiently technological species? All the free energy people are right, there's power to be had in "handwave zero point blah blah" energy.

But that means there's a lower energy level for the universe, and you're likely to collapse the false vacuum and destroy the universe if you try it.

So, the reason we don't see other technological species is because we can only exist in a universe where no other technological species has developed yet. Quantum immortality works, but it's not good news.