Okay, what's another wild-@$$ed theory to add to the BS?
I am totally making this up!!!!
Ben arranged a bunch of money somewhere, but he's got the IRS on him.
He grabs a friend to help him stage his 'disappearance".
Friend decides he wants the money for himself. Turns off Ben's air (we are assuming he was sidemount, but suppose he was just on a single to do the staging?)
Nature takes its course. Murdering friend takes Ben's body and throws body parts out on the way to Mexico.
End of total BS speculation.
Speculation, Part Deaux.
Perhaps "the money" was/is in the cave !
End of Speculation, Part Deaux.