This is indeed all too true, but surprisingly very few of them actually die while free soloing. It's nearly always something they took up later that was even more dangerous, such as base jumping, rope jumping, motorcycle riding, etc. that gets them. And even when it is rock climbing that does it, it tends to be on an easier route, with objective chance (Hersey) or suicide (Bachar) eventually deciding things.
One thing you can say about most serious free soloists is that they know their limits on rock.
If you mean, "died while freesoloing", you've got,
* Derek Hersey * John Bachar
off the top of my head. There are others,
https://en.wikipedia.org/wiki/Free_solo_climbing#Notable_acc...
Dan Osman died from a roped fall (jumped with the intent of the rope system to slow his fall), not a free solo. Dean Potter died from a wingsuit accident, which "literally" is probably the most dangerous hobby.
https://en.wikipedia.org/wiki/List_of_fatalities_due_to_wing...
"72 percent of fliers had witnessed death or serious injury, and 76 percent had experienced what they categorized as a “near miss.” http://www.newsweek.com/2014/09/12/thrilling-deadly-world-wi...
Dean Potter on Heaven, https://www.youtube.com/watch?v=wRUkolahw58
https://en.wikipedia.org/wiki/Free_solo_climbing#Notable_acc...
One of my favorite climbers and free soloists, Dan Osman, also died in an accident but not while free soloing. He was doing a 1000 ft rope jump (jumping from a cliff while connected to a climbing rope and catching oneself while trying not to slam back into the cliff face) when his rope snapped.
Here's two videos of him doing a rope jump and of him free soloing:
https://www.youtube.com/watch?v=EilwLq7w1bs
https://www.youtube.com/watch?v=wYbwZQ-QnMY (note the "dyno" at 1:09)
I mean that only 90% facetiously.
He seems genuinely sick of discussion about death, which at first shocked me (shouldn't someone tell him that almost every free soloist dies?! It's irresponsible not to!).
But if you listen to him, it's immediately apparent that he's fully cognizant of the situation. After just a few minutes even I was annoyed by the hypocrisy and judgment when someone questioned his risk assessment. And he has to deal with that almost every time he interacts with people outside of his inner circle. I can hardly imagine how frustrating that must be.