How is it any different than all the people who go hiking in the desert without knowing what they are in for? Or driving 4x4 trails, or climbing rocks/trees, or boating, or walking through urban areas, or running marathons?
Think about that last one. Every year in the US about 5 people will fall down dead because they choose to run a marathon that day. How can they keep doing it?
Nowadays every single special interest group has a forum like this. Every single forum will discuss, hash, rehash, flame about, and in general beat their chests for a month or so over each single incident. What went wrong, who is to blame, how stupid everyone involved was, how people just don't understand, how it will hurt the activity, how talking about it will hurt the activity, how... Well, let's just say that right now there are probably people posting on forums about the problem of untrained people who just don't know the hazards they are courting for activities ranging from mountain climbing to cooking. And they are right, those things are dangerous.
Now as far as I can tell about 10 people a year die diving in caves. The majority of those are OW certified, but the majority of ALL divers are OW certified. If 90% of divers are OW, and 80% of cave diving deaths are OW, that means that OW divers are under represented (and therefore avoiding the risks that people with more training are taking)...even though OW certified divers make up the largest category. That's a bit of math most people forget to do when they look at statistics.
For scale: In the USA about 80 people per year die in above-water caves. About 900 die riding bicycles.
So why do they? Obviously it seemed like a good idea at the time. Who hasn't had a moment like that in their life? Usually you get through it, sometimes people don't. Nature is an uncaring bit.....