Well, Iguanas were "the" reptile to get back in the day. Now, other, smaller, more predictable, more handleable, easier to care for, friendlier animals are available. I had iguanas, and they both died because our VET at the time recieved newsletters stating that high protein diets, including catfood and dogfood made them grow faster. When we brought them back in for calcium proiblems and gout a year or so later, he told us that it wasnt' a good idea...they had NEW info.
So, I was at the cutting edge back then, and our poor iguanas suffered as a result. They start out so cute and small and cheap (ours were $40 each, and they were tiny), they are easy to impulse buy.
Plus, people think a herbivore is a plus - that it is going to be easier to feed them. not the case. It's hard to balance their diet, and they need a lot of space.
I raise chameleons. Iguanas are far more challenging, for a number of reasons.