tldr; It is incoherent to talk about a "you" which stretches through time. Instead, we should think of a series of similar mind-moments.
Once upon a time, there was a little boy, who answered to the name Lucas Sloan and was scared of dying. I too answer to the name Lucas Sloan, and I remember being afraid of dying. Little Lucas wasn't scared of the present state of affairs, but it is fairly obvious that Little Lucas isn't around anymore. By any practical definition, Little Lucas is dead, he only exists as a memory in my mind and more indirectly in the minds of others. Little Lucas did not care that other people remembered him, he cared that he did not die. So what is this death thing, if Little Lucas was scared of it, but was not scared of the present situation?
I would now like to introduce the term mind-moment. I'm not sure quite how to define that, it may have to mean a single plank-time snapshot of a mind, or it might be as much as a couple weeks. I doubt that what I mean by this is anywhere near the upper bound I just gave, a more likely upper bound might be about a second - about the time it takes to notice something and realize something is going on.
Confusion about the exact definition of mind-moment aside, I think it is obvious that Little Lucas and I are separate mind-moments. And the fact of the matter is that the mind moment that was Little Lucas no longer exists, that mind-moment is definitely dead, gone, kaput. In fact, if I'm right about what I mean by mind-moment, many mind-moments have ceased exist since I started writing this. And frankly, both of those things are, in fact, good. What would the point be of constantly re-running the same mind-moment over and over again? I certainly don´t want to be caught in a time loop till the end of time, even if I couldn't tell that I was – that would be as much a waste of the future as converting the stars into orgasmium. I want to experience new things, I want to grow and learn. But the problem is that my use of the word I is incoherent - the "me" that experiences those new things, that knows more than I do, is not me. My time is passing, soon enough, I will be the Little Lucas remembered only because he had some interesting ideas.
It's not that I don't want to die, it's that I want there to, in the future, exist happy, fulfilled mind-moments that remember being me. This model neatly solves the problem of the anthropic trilemma, you shouldn't anticipate being one of the winners or losers of the lottery, you should anticipate that at a certain point there will be x mind-moments who won or lost the lottery and remember being you. However, it does make the morality of death a lot more complicated. We shouldn't talk about killing as the action that breaks the status quo, we should instead say that each mind-moment needs to be created, and that mind-moments, once created have a right to the creation of their successors, each of whom retains that right.
This would all be quite simple if each mind-moment had one and only one possible successor. However, this is not the case. In writing this sentence, I could use the verb "use" or "write" and both choices require a separate mind-moment. Which mind-moment should be created? Are we obligated to create both? What if there are a million possible mind-moment successors? Are we obligated to create all of them? I don't think so. I still believe that the creation of minds is an active choice, so we shouldn't create minds without cause. Recasting life as a series of decisions to create mind moments explains the attractiveness of quantum suicide, you aren't killing yourself, you are refusing to create certain mind-moments.
I still have some questions about life and death. For example, how quickly do we have to create these mind moments? It seems wrong to delay the creation of a subsequent mind-moment until the end of the universe, but as long as the next mind moment hasn't been created it isn't entitled to its successor. Also, are we obligated to create on the best/happiest/most fulfilled successor mind-moments? It might seem so in a classical universe, but in many worlds, wouldn't doing so result in horrendous duplication of effort?