Although the financial aspect is a big part of it, I think it is fiercely compounded by the majority's lack of knowledge on animal husbandry and exotic care. Everybody thinks you just throw it in a tank with a light food and water and thats it. "He'll eat if he's hungry" mentality.
We need to push for a movement that enlightens the Average Joe about the actual costs of keeping an animal so that they consider those vet bills, running costs, uvb lamps, etc.
then again, I'm sure a ton of people buy the animal for the "ooh ahh" factor and then if it dies then just spend $25 and get another one rather than fight the cost of care...