Cave diving is a much more difficult version of diving. Many of the Thai seal team divers are open water divers. This is why there was a large contingent of foreign divers involved. Those with the requisite skills levels are widely dispersed. It's entirely likely that Saman Gunan could have done a hundred more open water dives and survived then all, but due to the difficult conditions in this situation it is possible he got disoriented and/or panicked and ran out of air. I think because the boys survived many people perhaps underestimate the difficulty of the situation now that it is resolved.