If they had died in a house firing doing nothing wrong I'd agree with you. I don't hold much sympathy for people that die doing extremely dangerous things. Even less for people doing something only a very small percentage of people can afford to do.
It's about having sympathy for their families and those they left behind. You couldn't honestly say that if another Space Shuttle (heaven forbid) blew up, full of people doing an 'extremely dangerous thing' you wouldn't have sympathy for those left on the ground who have to pick up the pieces?
At least the people on a Shuttle are doing something useful unlike climbing a mountain in the middle of winter. One can argue whether a Shuttle flight is sufficiently useful to warrant the risk involved, but at least it wasn't a recreational jaunt which is about all that most mountain climbing is.
