I think part of the problem is that people think this is an all-or-nothing deal and you'll get kicked out of the club and have your decoder ring revoked if someone catches you eating a peanut.
Honestly, I have not completely given up the things I love, I've just severely reduced the amount of sugar and carbs I consume (hell, I'm sipping on a Pepsi Throwback while typing this--one of the two I'll drink during the week), and it still works pretty well--I think it'd be good if more people looked at it this way. You can still lose a pound per week on the 80/20 rule, even if it's like 70/30, etc. ... just don't use "well, I can't totally give up carbs and sugar" as an excuse to not even try to cut back.
Having said that, I'm having that issue with my husband--if I don't make dinner, he'll have bread with processed cheese on it, chips, and soda. I've tried to talk him into at least cutting back on the carbs like I have, and he'll just laugh it off like it's impossible for him. It's especially annoying because he has health problems that I think could be improved if he improved his diet, but he won't even try it.
I mean, I used to take up about the bottom 2 inches of my coffee cup with sugar, thinking that was the only way I could ever drink coffee because I'd been doing it since I was like 10 ... and now I only use one spoonful each of sugar and truvia. If I can cut way back on sugar, anybody can.