You make a very valid point, as we all know of people who blow through every dollar they have, then whine and cry about not having the money for rent, car pmt, etc.
I can provide an excellent example. My ex wife had an uncle and aunt who were financially well off, although you'd never really know it to look at their home, car, etc. Anyway, her aunt passed away and I attended the funeral. (Her family thought more of me than they did her) While there I spoke with her uncle, who confided in me that he and his wife had saved almost 3 million over their time together, and since they had no children, most of the money would go to my ex and her brother. Some would go to charity.
He passed away a year later, and I learned from my son that he had left his mom, my ex, $900,000. My son even said at the time that she and her husband would go through it in 5 years time. I said two. It lasted less than two. The things they just blew the money on was just unbelievable. Now they live in a trailer park, and had to sell his new truck they had bought.
A more selfish person I have never met. At the time, our son was going to turn 16 soon and I had promised him that I would buy him a gently used car. Did she ever offer to help, or even buy one for him herself? NO. Did she put any back, in any form, for our son's future? NO. Vacations, new cars, ordering through Doordash EVERY DAY for EVERY MEAL, jewelry, etc, etc, etc. That's where her money went. So yes, people like her CHOOSE to spend every dime they have, you are correct. You simply cannot reason with such people, you just can't. You can't fix stupid and you can't fix selfishness.