People Choose When to Die?

One economist, who I think was Gary Becker of U of Chicago, once said, more or less people choose when to die; Heavy smokers or gangsters can be said to choose to die younger, otherwise people don't choose such careers.

However, I don't think people are so rational to know the ends, and it's a little surprise to hear that there's one who chooses the date to die. Honestly, no matter what reason she had, I cannot feel happy to think she must have had another choice to make; I do not think that her decision is true for those who are suffering from the same disease and having the same fate as she had.