I don't have a model which I believe with certainty, and I think it is a mistake to have one, unless you know sufficiently more than modern physics knows.
Why do you think that your consciousness always moves to the branch where you live, but not at random? Quantum lotteries, quantum immortality and the like require not just MWI, but MWI with a bunch of additional assumptions. And if some QM interpretation flavor violates causality, it is more an argument against such an interpretation, than against causality.
The thing I don't like about such way of winning quantum lotteries is that they require non-local physical laws. Imagine that a machine shoots you iff some condition is not fulfilled; you say that you will therefore find yourself in the branch where the condition is fulfilled. But the machine won't kill you instantly, so the choice of branch at time t must be done based on what happens at time t + dt.
I don't have a model which I believe with certainty, and I think it is a mistake to have one, unless you know sufficiently more than modern physics knows.
Note that I said provided MWI is true.
Why do you think that your consciousness always moves to the branch where you live, but not at random?
I think that, given MWI, your consciousness is in any world in which you exist, so that if you kill yourself in the other worlds, you only exist in worlds that you didn't kill yourself. I'm not sure what else could happen; obviously you can't exist in the world...
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?