Have you ever read Ruby Payne’s “A Framework For Understanding Poverty”?
Basically, it was written to help middle-class teachers understand the backgrounds of their students who come from poverty. Poverty isn’t just a lack-of-money, but poverty can be a lifestyle and a general lack-of-resources. The more resources you lack, the harder it is to get out of poverty.
One of the things, for example, is how money is perceived. It’s perceived as something that never sticks around, so you have to hurry up and spend it on stuff that brings you happiness, or stuff that brings you status in your social circle, before it gets spent on other stuff. (Which might well be the electric bill, the mortgage, gas for the car, repairs, etc.) Because life is generally planned from paycheck to paycheck, there is no long-term perspective that encourages people to save up against the unexpected (the check engine light comes on, I had to spend the rent money on a plane ticket for my mom’s funeral, I want to buy my wife a Keurig for Christmas and the kids VR goggles instead of paying the mortgage).
(Those above are all real-life examples of what people have told me to my face as to why paying rent wasn’t their priority.)
I’m happy that your husband and his siblings seem to have escaped from that mentality. One of the things that I’ve discovered in the course of being a landlord is that grown adults can have a middle-class paycheck, but still have an impoverished lifestyle. Reading up on Ruby Payne might be broad generalizations---- but it helps give a context for how some people can consistently make horrible decisions regarding their financial well-being.