To our perspective, this is from (2): all advanced civilizations die off in massive industrial accidents; God alone knows what they thought they were trying to accomplish.
Also, wouldn't there still be people who chose to stay behind? Unless we're talking about something that blows up entire solar systems, it would remain possible for members of the advanced civilization to opt out of this very tempting choice. And I feel confident that for at least some civilizations, there will be people who refuse to bite and say "OK, you guys go inhabit a tiny subset of all universes as gods; we will stay behind and occupy all remaining universes as mortals."
If this process keeps going on for a while, you end up with a residual civilization composed overwhelmingly of people who harbor strong memes against taking extremely low-probability, high-payoff risks, even if the probability arithmetic indicates doing so.
For your proposal to work, it has to be an all-or-nothing thing that affects every member of the species, or affects a broad enough area that the people who aren't interested have no choice but to play along because there's no escape from the blast radius of the "might make you God, probably kills you" machine. The former is unlikely because it requires technomagic; the latter strikes me as possible only if it triggers events we could detect at long range.
I admit that your analysis is quite convincing, but will play the devil's advocate just for fun:
1) We see a lot of cataclysmic events in our universe, the source of which are at least uncertain. It is definitely a possibility that some of them could originate from super-advanced civilizations going up in flame. (Maybe due to accidents or deliberate effort)
2) Maybe the minority that does not approve trickling down the narrow branch is even less inclined to witness the spectacular death of the elite and live on in a resource-exhausted section of the universe...
We have a sample of one modern human civilization, but there are some hints on how likely it was to happen.
Major types of hints are:
Data for:
Data against:
To me it looks like life, animals with nervous systems, Upper Paleolithic-style Homo, language, and behavioral modernity were all extremely unlikely events (notice how far ago they are - vaguely ~3.5bln, ~600mln, ~3mln, ~200k or ~600k, ~50k years ago) - except perhaps language and behavioral modernity might have been linked with each other, if language was relatively late (Homo sapiens only) and behavioral modernity more gradual (and its apparent suddenness is an artifact). Once we have behavioral modernity, modern civilization seems almost inevitable. Your interpretation might vary of course, but at least now you have a lot of data to argue for your position, in convenient format.