Having read this entire thread and all of the similar material relating to the Tunnel Creek tragedy, none of us is in a position to answer the question "why?"
There is a survivor from this horrific event and only he can provide some insight into the "why?" of what they did. Perhaps in time he will have the confidence to shed light on the incident, but no doubt he is fully aware of the scrutiny he is / will be under. This man is going to need a lot of love and support to work his way through this experience.
As a child, my father would often ask me this question;
"If I do this, what could possibly happen?
We do not need to be looking for the perfect line for a potentially fatal event. Maybe you were on a groomer run and was hoping for a speed run. Did you check to make sure all was clear before hitting that kicker? Should I be pushing that very yellow, now red light? Six beers later, should I be behind the wheel? Will the next car see me if I step out from in front of this bus?
One does not need be on a mountain side for tragedy to pay a visit.
We should strive to live life to the fullest each and every day for ourselves, our loved ones and all of those around us. As a group of enthusiasts, we need to be diligent every time we encounter a situation that has potentially dire results.
My condolences to the family and friends of the deceased. May your loved ones rest in peace.