My take on this missing submarine is it's part of the thing where since Harambe the world operates on novelistic logic. Like, it's not even that it's poetic justice for these billionaires to die so much as that it's a dramatic event arising from the confluence of several major themes of the contemporary world
Also I’ll say the prospect of awaiting inevitable death trapped at the bottom of an ocean in an ersatz high tech tin can with a few other representatives of a wildly wealthy novelty-seeking class is very 80s horror, that could have been a Tales From the Crypt episode back when it was Black Mirror about yuppies.
(Fuck if I know how you’d shoehorn in the practical effects gore and tits.)