Assuming for a moment that Everett's interpretation is correct, there will eventually be a way to very confidently deduce this (and time, identity and consciousness work pretty much like described by Drescher IIRC - there is no continuation of consciousness, just memories, and nothing meaningful separates your identity from your copies):
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? 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.
This is obviously not applicable to e.g. humanity as it is, where self-destruction on any level is inconvenient, if at all possible, and generally not a nice thing to do. But would it theoretically make sense for intelligences like this to develop, and maybe even have an overwhelming tendency to develop in the long term? What if this is one of the vast amount of branches where everyone in the observable universe pretty much failed to have a good enough time and a bright enough future and just offed themselves before interstellar travel etc., because a sufficiently advanced civilization sees it's just not a big deal in an Everett multiverse?
(There's probably a lot that I've missed here as I have no deep knowledge regarding the MWI, and my reading history so far only touches on this kind of stuff in general, but yay stupid questions thread.)
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
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