Although I do think Jay if he's sadly passed, did so after hiking in the heat and not having any water/cover etc, there remains a big question over *why* he went to that Airbnb.
It's too much to suggest that drugs weren't somehow involved. There is no real reason for him to go there - in my humble opinion - unless it was for some sort of 'deal' or drugs-related activity.
Everything the British man who rented the Airbnb has said is nonsensical. Jay's mates did not 'abandon' or 'leave him'. In fact every report has stated that Lucy especially tried to persuade Jay to go WITH her back to their apartment.
Yes Jay and his friends had been socialising with the two older men during the holiday, but I don't for one minute believe he went with them all the way to that remote rental just to enjoy a chat...
Now, it may be that whatever went on at the rental had nothing to do with Jay's subsequent disappearance; it may be that when their 'business' was concluded, Jay was tired and decided to head off, and then got lost, dehydrated, etc and sadly simply hasn't been found yet.
Or - and I could see this - he decided to abscond with something he saw at the rental. Whether that's a watch, or drugs, or cash, he grabbed it and then knew he had to get the hell out of there.
That, again in my humble view, would explain why when on the phone to his friends he apparently stated he 'could not' return to the rental to get a lift/water/help.
He couldn't go back because by then, the two men might have discovered that he'd pinched something.
This also explains why he deviated from the path - he knew they might come looking from him.