In his discussion of "cryocrastination", AndrewH makes a pretty good point. There may be some better things you can do with the money you'd spend on cryonics insurance. The sort of people who are into cryonics would probably accept that donating it to the Singularity Institute is probably, all in all, a higher utility use of however many dollars. Andrew's conclusion is that you should figure out what maximizes utility and do it, regardless of how small a contribution is involved. He's right, but I want to use the same example to push a point that is very slightly different, or maybe a little more general, or maybe the exact same one but phrased differently.
Consider an argument frequently made when politicians are discussing the budget. I frequently hear people say it would cost between ten and twenty billion dollars a year to feed all the hungry people in the world. I don't know if that's true or not, and considering the recent skepticism about aid it probably isn't, but let's say the politicians believe it. So when they look at (for example) NASA's budget of fifteen billion dollars, they say something like "It's criminal to be spending all this money on space probes and radio telescopes when it could eliminate world hunger, so let's cut NASA's budget."
You see the problem? When we cut NASA's budget, it doesn't immediately go into the "solve world hunger" fund. It goes into the rest of the budget, and probably gets divided among the Congressman Johnson Memorial Fisheries Museum and purchasing twelve-thousand-dollar staplers.
The same is true of cryocrastination. Unless you actually take that money you would have spent on cryonics and donate it to the Singularity Institute, it's going into the rest of your budget, and you'll probably spend it on coffee and plasma TVs and famous statistician trading cards and whatever else.
I find myself frequently making this error in the following way: a beggar asks me for money, and I want to give it to them on the grounds that they have activated my urge to help people. Then think to myself "I can't justify giving the money to this beggar when it would help many more people if I gave it to a responsible charity." So I say no, and forget all about it, and never give the money to anyone. Even though (from a charity point of view) I know of a superior alternative to giving the money to the beggar, I would still be better off just giving the beggar the money!
All this means that for any entity that does not use its resources with maximum efficiency, the opportunity cost of spending a certain amount of resources should not be calculated as what you'd get earn from the best possible use of those resources, but what you'll earn from the use of those resources which you expect to actually occur.
(This is somewhat tangential to your actual comment so don't look on this like it's a counter-argument.)
This idea of using incentives to guide their behavior is to impose our value system on them. It's one thing to say that you don't want to help these people at all, but to actually try to use the power (through money) to influence the way these people live their lives is morally not justified. Just because we have the power, doesn't mean we have the moral right to say how each of these individuals should live their lives.
Of course, we do impose our value systems in using our money in other circumstances too, but in this context we have a really unbalanced relationship where the other side typically doesn't have this particular power at all and those considering helping have loads.
If you are concretely deciding whether or not to give money to someone begging and you base the decision on what the person is going to spend the money on, you are using your power in this context to try to dictate how the other person lives his/her life. What if the thing he most needs right now is to buy a pack of cigarettes or get drunk or whatever? What gives you the right the impose your values on the person?
All credit to Aaron Swartz.
I am uneasy with that sentiment although I'm having a hard time putting my finger one exactly why. But this is how I see it: there are vastly more people in the world than I could possibly ever help and some of them are so poor and downtrodden that they spend most of their money on food since they can't afford luxuries such as drugs. Eventually, I might give money to the drug user if I had solved all the other problems first, but I would prefer my money to be spent on something more essential for survival first before I turn to subsidizing people's luxury spending.
Imposing my values on somebody seems to more aptly describe a situation where I use authority to compel the drug user to not use drugs.