I think that if you are on a v low income and having to count every penny, that a 'treat' assumes more importance than if you are not. People are right that some people could move more and eat less and it is simple. But it's not simple when you're in that situation because the crisps or the chocolate or whatever are pleasurable and good and going out for a run isn't fun as such, at least not until you have done it often enough to see the benefits. And there isn't any money to have a different kind of non-fattening treat because those are loads more expensive usually.
And if you are on your own with kids or working shifts and juggling childcare where do you get the time anyway? You could get up earlier and walk a couple of miles to work, but if you are tired tired tired from living your life one paycheck to the next and worrying about where the next supermarket shop is coming from, you don't feel like it. You feel like a little treat, and it's only 50p for a packet of biscuits. And things get slowly worse and then of course you don't feel like getting out there and exercising because you know you are already fat and you feel like people will be looking at the fat person running and you don't want it and you can't afford decent supportive trainers anyway and who will watch the kids while you do it? And then you feel miserable because you are fat and you are doing life wrong and then you feel worse and you do, really, need a treat and you need something to just be fun in your life.
Who was that woman on YouTube a while back who talked about why poor people don't give up smoking? She summed it up perfectly. If you can only get halfway there, however long you try, what's the point? You'll never ever get there so you might as well have the chips or the cigarettes or the wine or the whatever and enjoy what is here now.
This isn't me, btw, it's just what I see in other people's lives. I can't judge them for it. I am sure I would be the same in their positions, which I am fortunate enough not to be in. I can afford the non-fattening things that make life OK. It's frankly awful that people are still living like this (it's not their fault, it' society's fault, it really is, on all kinds of levels).