It's the mix of addictive, chemically engineered flavors and the millions of dollars spent in marketing their products and the whole "experience" that led not only you, but I think most of us to see fast food as something so awesome and desirable, when in fact it's just the opposite.
Coming from a 3rd world country I can relate going to these chains as a treat or a "luxury", this is something most of children (and adults) still think of these places, same people that sometimes you can hear saying "healthy food is too expensive", which is not, when you cook and consciously select season vegetables and stick to buying ingredients rather than prepared stuff.
Luckily for me, homemade foods made up the 99% of my diet as a kid, and I didn't grow too fond of fast food other than the occasional "treat", but lots of people grow up without that kind of luck, and carry on with bad eating habits for the rest of their lives, with all the health related issues that comes with eating processed foods regularly.
Really glad you could make that change in your life and managed to make your children prefer your food instead of that crap! Not easy in these days !