Alas, but no. The reason I don't expect my current decisions to be preserved into, say, the next year, is because I expect something crucial about my situation to change during the intervening period. For instance, take this example:
Don't want to move away from your parents today? well then you must never want to.
Sorry; that's just plain wrong. If I don't want to move away from my parents today, that's due to a number of reasons: I might be underage, still economically reliant upon them, still need to attend school, etc. On the other hand, I anticipate with high probability that at some point the above statements will no longer be true; there will come a point when I am no longer underage, no longer dependent, and ready to go to a fancy out-of-state college, say. The point is, I expect my decision to change because I expect the surrounding circumstances to change. If for some reason I was persuaded that I would forever remain an economically dependent minor, then perhaps I would want to stay with my parents forever.
Note that this is not the situation our supposed deathists find themselves in. They are not expecting some future change in their circumstances that would render death suddenly a thing that they want. They don't want to die today because they are (for example) living comfortably in a retirement home, interacting with their children and grandchildren. There is no reason to expect those conditions to change anytime soon barring death, and in particular, there is no reason to expect those conditions to change in such a manner as to make death preferable to life.
And for good reason: try to imagine a situation in which you are happily living your life one day, and suddenly want to die the next. All right, I bet that was pretty easy. Maybe you were kidnapped during the night and subjected to extremely painful torture that you were told would last for 50 years. Maybe you developed some mental disorder causing you to become rampantly suicidal. Or maybe it's just that you received a notice of foreclosure; that's been known to drive people to suicide, after all. Now let me add one more caveat. It has to be something you were expecting in advance--not necessarily that you knew it was going to happen on that day, but you knew it was going to happen someday.
Suddenly not so easy, is it? Death is one of those things for which your preferences should never change outside of some extreme circumstances that are minimally probable at best. If you don't want to die today, there will never come a day when you do want to die ("Oh, man, it's Tuesday! Wouldn't this be just a fantastic day to commit suicide!") barring the possibility of black swans. And that makes "wanting to die" a very different beast than "wanting to move out from my parents' house" indeed.
Note that this is not the situation our supposed deathists find themselves in. They are not expecting some future change in their circumstances that would render death suddenly a thing that they want.
Yes, they are. They are expecting their health to keep deteriorating.
Over and over again, someone says that living for a very long time would be a bad thing, and then some futurist tries to persuade them that their reasoning is faulty, telling them that they think that way now, but they'll change their minds when they're older.
The thing is, I don't see that happening. I live in a small town full of retirees, and those few I've asked about it are waiting for death peacefully. When I ask them about their ambitions, or things they still want to accomplish, they have none.
Suppose that people mean what they say. Why do they want to die?
The reason is obvious if you just watch them for a few years. They have nothing to live for. They have a great deal of free time, but nothing they really want to do with it. They like visiting friends and relatives, but only so often. The women knit. The men do yardwork. They both work in their gardens and watch a lot of TV. This observational sample is much larger than the few people I've asked.
You folks on LessWrong have lots of interests. You want to understand math, write stories, create start-ups, optimize your lives.
But face it. You're weird. And I mean that in a bad way, evolutionarily speaking. How many of you have kids?
Damn few. The LessWrong mindset is maladaptive. It leads to leaving behind fewer offspring. A well-adapted human cares above all about sex, love, family, and friends, and isn't distracted from those things by an ADD-ish fascination with type theory. That's why they probably have more sex, love, and friends than you do.
Most people do not have open-ended interests the way LWers do. If they have a hobby, it's something repetitive like fly-fishing or needlepoint that doesn't provide an endless frontier for discovery. They marry, they have kids, the kids grow up, they have grandkids, and they're done. If you ask them what the best thing in their life was, they'll say it was having kids. If you ask if they'd do it again, they'll laugh and say absolutely not.
We could get into a long argument over the evolution of aging, and whether people would remain eager to have kids if they remained physically young. Maybe some would. Some would not, though. Many young parents are looking forward to the day their kids leave.
A lot of interests in life are passing. You fall in love with a hobby, you learn it, you do it for a few years, then you get tired of it. The things that were fascinating when you were six hold no magic for you now. Pick up a toy soldier and try to play with it. You can't. Skateboarding seems awesome for about five years, and then everyone except Tony Hawk gets tired of it.
Having kids might be like that for some people. Thing is, it's literally the only thing humans have evolved to be interested in. Once you're tired of that, you're done. If some of you want to keep going, that's an accidental by-product of evolution. And there was no evolutionary pressure to exempt it from the common waning of interest with long exposure.
The way to convert deathists isn't to argue with them, but to get them interested in something. Twist them the way you're twisted.