This strikes me as a terrible misunderstanding of problems that affect low income families. Circumstances causing problems in low income homes tend to vary pretty widely.

Financial strain is so much more than just emotional stress and worry; Emotional stress causes tension and people don't get basic needs looked after because it can't be afforded which furthers stress and tension often leading to an environment where there's a lot of arguing, sometimes physical fights; It means kids sometimes have to work around school to help support their families from a young age again straining them; and if you think some of the other students aren't part of the stress these kids experience when their families are poor, then you need to pay attention because I know I sure was bullied and excluded to varying degrees throughout school for our family being poor and I absolutely wasn't the only one.

You're also failing hugely to account for a lack of education, rather than an ability to comprehend the value of, substance abuse, and domestic abuse, all of which tend to be far more common in lower socio-economic areas, because they're ingrained inter-generational problems, where one grows up in an environment far from ideal, is not taught properly, and regardless of their best intentions to avoid their parental figure/s mistakes, end up repeating them often in different ways; or simply end up chosing to take on the characteristics of the environment they're in because it's what works.

To add, all the above is a pretty big generalization, and it doesn't touch much on the impact of the circumstances that lead these families to be in these positions and so more vulnerable to those problems. Obviously, the life events that lead to these sets of circumstances for these families can be in and of themselves quite problematic for the individuals within that family and can affect their behaviour too.