I lived a significant portion of my life in pretty severe poverty; I was raised in it. It requires a decent amount of discipline to not waste money even when you are hungry and can't pay the bills, and many poor people do not have that discipline and therefore stay poor. Many non-poor people have the same lack of discipline but can simply afford to be more wasteful. Given two choices that solve an immediate problem (e.g. hunger) people will often choose the one that is most wasteful of their money even though they know they are poor.
I was never the world's most disciplined person but I did manage to bootstrap myself out of poverty in fairly boring fashion working low-paying jobs. As long as I had an income (never guaranteed) I always managed to spend less money than I earned. It is pretty shocking the percentage of people in poverty that are obviously wasteful with their limited resources but it also explains their long term outcome.
I earn a fine income today but my spending stopped rising with my income a long time ago. Old habits of not spending frivolously on low-value things die hard I guess.