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The question is not: What makes poor people poor? It is: Is there any way to avoid being poor?
To paraphrase Ben Shapiro, (1) finish high school, (2) get a job (any job), and (3) don't have kids before you get married. If you do those three things, there is a very small chance you will be poor initially and remain poor.
Many factors can make "middle class" people poor:
Death of a spouse,
Medical bills,
Other personal catastrophe,
Having kids and no husband,
Not having a job,
Substance abuse.
Lord knows, starting life as an "emancipated single adult" today can put you behind the 8-ball. I pity people who don't have any family to help them get started. (Although my family gave me squat).
Glad I'm past that stage of my life.