Id like to state, as a beginner, what I have learned from this incident.
No matter how many dives one has, no matter how much training one has, no matter how many people can personally vouch for a person as "the best diver they've ever seen", you too can die in a spectacularly easy manner when overconfidence in your abilities becomes your buddy.
How can 4 guys, who have probably councelled people never to do what they did, allow themselves to come up with the plan, or lack thereof, that they came up with??
Where were the alarms in their heads?
Overconfidence, invincibility. No thanks, Ill dive scared and prepared.