People to dangerous things for leisure all the time. Mountain climbing, deep sea diving, extreme skiing are all among activities that can cause you to literally die.
Likewise, some people like to go to places that are less travelled even if it's dangerous. For some the danger is the thrill.
That doesn't mean they deserve mocking if it all goes wrong, anymore than the person who stumbles, falls and dies whilst undertaking a very difficult climb does.
This couple were intrepid wanderers. It was what they did and they don't deserve locking up or people on internet taking the mick out of them. Imagine what they're going through, if it were you or loved ones, would you like a ton of strangers calling you stupid and saying they have no sympathy?
Does internet just make people crass, because I honestly do not believe for a moment that anyone here would really say these things to them or truly has no sympathy. Deep down you're appalled at what they might suffer. It's an unpleasant thought.