Having trouble loading the past pages so apologies if I repeat things!
Having seen a timeline on television news where he was partying until 5am at a club before he left with the two men I think it sounds like he was going with them for more drugs. He then was known to leave their flat at only 7.30 (after a long drive there) and spoke to a witness asking about a bus. After she drove somewhere and was coming back she said she saw him walking the wrong way.
All evidence points to him still being inebriated/intoxicated/high, up all night, confused, and then walked into tough mountainous terrain, and most likely he met with misadventure/exposure/dehydration/accident. It only seems like a mystery because he’s not been found but sadly that can often be the case in this kind of tough terrain. (Some are never found or not discovered for months or years.)