[gjm11]

It's measuring the value of their life relative to the value of money, for them. In many situations that isn't the statistic you actually care about.

(For the avoidance of doubt: my previous comment wasn't trying to claim that the "statistical value of a life", measured in such a way, is a good measure of how much a person values their life in non-monetary terms, or anything like that. I was just objecting to the specific claim I was responding to, namely that the "statistical value of a life" is measuring only its value as a future income stream.)

Very very crudely, the value of a small gain in money is something like inversely proportional to the amount you have already, which means that the value of a given amount of wealth increases something like logarithmically with the amount of money, and either of these means that financial institutions like markets care about people's interests roughly proportionally to their wealth. Everything in this paragraph is pure handwaving, but I find it a useful intuition.