I don't think it's that crazy he went off the road. He was travelling North, either mistakenly or misled by apple maps, the first thing he would have come to is a cafe. The cafe was shut - it opened at 10am. Opposite the cafe was a path leading up to a transmitter of sorts. It would make absolute sense to walk up a hundred yards or so, to get a good view of his surroundings. This is the
view on Google Earth looking towards the Baranco Juan Lopez, where it appears his body was found:
View attachment 518105
He would have seen the outbuilding or cottage at C, notably (if you zoom in on Google Earth) with some clear plastic water containers against the near wall. Given that he was thirsty it's not inconceivable he would leave the road at A, walk down a gravel path - suitable for 4x4s - towards B. Along that track is where has last known location is. Note: some people have imagined him jumping off the road to evade people - he was on the track so this seems extremely unlikely.
Having got to the building at C, and presumably finding it empty, the next building would have come into view at D. There's actually 4 buildings along the track, 2 seems OK, the third is pretty derelict, and the fourth is a little off the trail and nothing but walls. You can see the latter two on the YouTube videos from people who've walked all the way to the beach. I think it's possible he moved on to the second building before getting into the sunk costs fallacy zone and continued to the river.
One thing worth mentioning is that the overgrown ravine footage we've seen is what he fell into, not what he was walking through. Depending how far he got there may have still been a half decent trail.
As to why he left, the obvious answer to me is that the old fellas he left with were knackered and had no intention of giving him a lift any time soon. As to the idea of him being scared on leaving, neither the two calls we know he made, the fact he popped out for cigarettes and went back, and Orphelia's description of him don't suggest that at all. The only person who has is a failed detective turned gutter press reporter who has a vested interest in keeping the mystery up. Maybe there is more to it, but I can't see it.