I was the same age as you when I was in McD’s, looking at my Super Size combo meal, that mountain of fries, and thought, “I can’t eat this crap anymore “.
There have been a number of books on how McD’s changed America’s eating habits.
People like it for no other reason than it’s fast. It really doesn’t taste good, there are better burgers out there, but it’s fast.
If there is one fast food burger joint I find decent, it would be Wendy’s.