Should beings/societies/systems clever enough to figure this out (and with something like preferences or values) just seek to self-destruct if they find themselves in a sufficiently suboptimal branch, suffering or otherwise worse off than they plausibly could be?
Not really. If you're in a suboptimal branch, but still doing better than if you didn't exist at all, then you aren't making the world better off by self-destructing regardless of whether other branches exist.
Committing to give up in case things go awry would lessen the impact of setbacks and increase the proportion of branches where everything is stellar, just due to good luck. Keep the best worlds, discard the rest, avoid a lot of hassle.
It would not increase the proportion (technically, you want to be talking about measure here, but the distinction isn't important for this particular discussion) of branches where everything is stellar - just the proportion of branches where everything is stellar out of the total proportion of branches where you are alive, which isn't so important. To see this, imagine you have two branches, one where things are going poorly and one where things are going great. The proportion of branches where things are going stellar is 1/2. Now suppose that the being/society/system that is going poorly self-destructs. The proportion of branches where things are going stellar is still 1/2, but now you have a branch where instead of having a being/society/system that is going poorly, you have no being/society/system at all.
Thanks! Ah, I'm probably just typical-minding like there's no tomorrow, but I find it inconceivable to place much value on the amount of branches you exist in. The perceived continuation of your consciousness will still go on as long as there are beings with your memories in some branch: in general, it seems to me that if you say you "want to keep living", you mean you want there to be copies of you in some or the possible futures, waking up the next morning doing stuff present-you would have done, recalling what present-you thought yesterday, an...
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