To me the reaction to the sub story had two parts.
One was the fascination with the extraordinary circumstances. A submersible going missing while exploring a deep ocean wreck doesn't happen often, and the unique situation garnered a lot of extra coverage. Refugees getting lost in the ocean happens disturbingly often, on the other hand, so there isn't much to distinguish that story from the rest.
The other, far more interesting piece was the fact that a bunch of billionaires were squashed to death by a 4,000m column of cold, unfeeling ocean water as a direct result of their own hubris. Income inequality, the "eat the rich" undercurrent in society today, and the glaring problems with the shoddy submersible they climbed into, culminated in this absolute lack of sympathy the likes of which I don't think I've ever witnessed before.
And honestly, I'm here for it. It shows how few fucks people have left for the upper crust of society. We're reaching a breaking point. This macabre schadenfreude is a symptom of a much larger problem.