Well they race 300mph cars for a living, its dangerous, and they know if something goes wrong they could die, but they love it enough to continue doing it.
Very sad to see that accident though, because I've seen a few like that on drag strips with large run off areas and some have walked away with barely any injuries, the initial explosion and fire surely wouldn't have killed him, it must have been the massive impact into that wall. I think they will seriously need to think about that drag strips safety, because by the looks of it that car launched extremely high over that wall, if there is a road on the other side then it could have landed on it, or debris could land on it.