As we all - assuming we all here on HN do relatively intellectual work - can attest, thinking and deciding have energy and exhaustion costs and we have a finite capacity after which we must recharge and rest.
And many of us are familiar with how stress (deadlines, conflicts at home, weather, etc.) tax us even further, reducing our ability to think well and decide well, and leading, sometimes, to poor decisions...
...that bring their own stress and workload.
Imagine if everyday the bulk of your decision making was literally about every dollar: heat and lights or shoes? Shoes or food? Food or healthcare? Healthcare of rent? Rent or heat and light?
You would do the same thing we do when we are coding something complex and need to make progress. You would pick a thing, do something simple that isn't really enough but is enough for now, slap hic sunt draconis in a comment, and move on. Hopefully you will get back to it.
People choose the easy, convenient, less good for them food because that gives more time to consider their other trade offs, maybe even to breathe long enough to reduce some of their stress.
And they may never get back to that choice, because the choices, the strains, never end.
Poverty is a vicious circle of stress and decline. Yes, there are people who make it out, just like there are people who make the NBA or the NHL. Most people, though, suffer. Literally.
It doesn't matter how people get poor. What matters is that poor is hard, harder than most anything most of us will ever face. What matters is that we respond with compassion and consideration and perhaps try to see beyond fault and responsibility and instead try to do something to amend those situations.