Most people here probably agree with you that poor people tend to have worse impulse control. But you seem totally unaware of how significantly stress, trauma, or desperation affect impulse control. It's more than just stress about paying the bills. I tutored reading at an intercity elementary school and there were kids there who had family members incarcerated or murdered, homes foreclosed, parents making the local headlines for child abuse, etc. One boy I taught had to move out of his house because someone shot it up in a driveby looking for his older brother. A girl from a refugee family had 19 siblings and a physically abusive, alcoholic father. My coworker taught a boy whose parents were both in prison for murder. It was not uncommon to see little kids wearing RIP shirts for friends and family members. These stories are so much more common than you'd think. I'm not being hyperbolic, look at gunshot and homocide maps for Chicago in a single year:
https://lh5.googleusercontent.com/-Yt65uE9YlMk/UR7-1mGIo8I/A...
https://www.google.com/maps/d/viewer?oe=UTF8&source=embed&ie...
Sure, a phenomenally resilient person can make it out of horrible circumstances, but the average person isn't able to. I personally don't think I would have fared well if I grew up in a bad environment. As a younger person I was angry and depressed enough already without the reality of hearing gunshots nightly, losing family members, facing systemic discrimination, going to bed hungry, etc. I had a great family and I still fucked up along the way sometimes. I also had a support system that allowed me to take the risks that made me independent and not poor today.
I somewhat disagree with your last point too. I grew up in the US but now live in a very poor country. The struggle is bad in both countries, just different.