I'm sure they do. But the chances of dying on board of an experimental submarine which is subjected to absolutely insane pressures are probably quite a bit higher still than the chances of dying on K2. But whether it's higher than the Titanic exploration missions is not the same as the
manned Titanic missions of which there have only been very few.
Those things work right up to the moment that they do not, this stuff is at the cutting edge of technology and tourists simply have absolutely no place there. The only reason those rich folks tend to do stuff like this is because they like to brag about such stuff, not because they're interested in the science behind it (if they were they likely wouldn't go). The Titanic is less accessible than space.