According to the Quantum Immortality hypothesis, you should take this deal, because in all quantum branches where you will exist you get million dollars, and the quantum branches where you don't exist are simply not your problem.

Why do people quietly assume QI implies a save-point-like functionality, where you continue from a convenient-to-your-conscious-mind position?

QI doesn't imply you only wake up in the universes where you weren't killed. You also wake up in universes where the killing was botched. You also wake up in universes where the scenario was a lie and you're now a slave in an underground mine. You also wake up in a myriad of quantum branches where your mind has fractured into discontinuity and exists, a fraction of a second each, across myriad distances of space and time, forming briefly as matter and energy randomly, and against great odds, configure into something that runs your mind for a brief period of time before falling back into chaos. And all of that is assuming your mind actually -stopped- running while you were asleep; the kinds of universes you wake up into if your mind -didn't- stop running while you were asleep should be expected to be much uglier.

Your mind appears, on average, wherever your mind is most likely to appear, not where you would naively expect your mind to appear, nor where it would be convenient for your mind to appear.

Given that:

If you said yes, imagine that there are two quantum random number generators available. One of them displays "WIN" with probability 99.99% and "LOSE" with probability 0.01%. The other displays "WIN" with probability 0.01% and "LOSE" with probability 99.99%. Do you have any preference at all about which of these two generators should be used in your case?

Given that somebody says yes, they should have a preference, yes. The more likely winning is, the -less- likely they are going to end up in a hellish existence they didn't anticipate at all.