HFCS is evil and outlawed in a lot of the civilized world. It's a known cause of cancer and tricks the brain into eating more.

It has such a high caloric density, a survival instinct inside the human brain kicks in. It says: wow this is really good, we don't get many opportunities to eat something this good, eat as much of it as you can. This makes sense in a cave man survival scenario, where you happen on some honey or sugary fermented fruits. Then you have a bigger chance of surviving if you eat as much of it as you possibly can. But in modern life where we have an infinite supply of these things it's a killer.