Under MWI, you can win a lottery just by entering it; committing suicide is not necessary. Of course, almost all of you will lose.
Replace "win a lottery" with "have a subjective probability of ~1 of winning a lottery".
All you're doing in quantum lotteries is deciding you really, REALLY don't care about the case where you lose, to the point that you want to not experience those branches at all, to the point that you'd kill yourself if you find yourself stuck in them.
That's wrong. If I found myself stuck in one, I would prefer to live; that's why I need a very strong precommitment, enforced by something I can't turn off.
You haven't gone out and changed the universe in any way (other than almost certainly killing yourself).
Here's where we differ; I identify every copy of me as "me", and deny any meaningful sense in which I can talk about which one "I" am before anything has diverged (or, in fact, before I have knowledge that excludes some of me). So there's no sense in which I "might" die, some of me certainly will, and some won't, and the end state of affairs is better given some conditions (like selfishness, no pain on death, and lots of other technicalities).
That's wrong. If I found myself stuck in one, I would prefer to live; that's why I need a very strong precommitment, enforced by something I can't turn off.
I mean, you_now would prefer to kill you_then.
As for your last paragraph, the framing was from a global point of view, and probability in this case is the deterministic, Quantum-Measure-based sort.
A self-modifying AI is built to serve humanity. The builders know, of course, that this is much riskier than it seems, because its success would render their own observations extremely rare. To solve the problem, they direct the AI to create billions of simulated humanities in the hope that this will serve as a Schelling point to them, and make their own universe almost certainly simulated.
Plausible?