One way to see it:

  1) Eventually you will die, no matter what. It can be the most mundane thing. Slipping on a ketchup splatter can cause great damage for example.

  2) It's a profession where you intentionally kill people, so, that changes the calculation for your own risk.

  3) It's a unique opportunity.

  4) Gives a sense of living / be in history books for his family.

> It's a profession where you intentionally kill people

Not being an astronaut (or being a test pilot, for that matter). That's the context in which he was speaking.