I think in a world where slitting someone’s throat for few thousand dollars (in some countries for few hundreds to just few) isn’t unheard of, I don’t know in what way people would find such scams inconceivable. I think the reason squarely is people being naive, or stupid, greedy, desperate (for love, better X times returns etc) etc - or a combination of these. And yes, they are victims, yes.
Keep in mind some of us still grow up in places where we can leave our cars/homes unlocked. Obviously extending that feeling to the entire world is naive, but it's also pretty understandable for our now elderly population..