Why are some communities poor?

Is it due to external and structural factors such as exploitation by foreigners or neoliberalism or racism?
Or, is due to internal factors such as culture and breakdown of families or moral values?
Why did poor working class whites recently help elect a billionaire with a history of exploiting workers to be president of the USA?

For Christmas, I (along with several other family members) received a copy of Hillbilly Elegy: A Memoir of a Family and Culture in Crisis by J. D. Vance.

I enjoyed reading it and would recommend it for three reasons.
First, it is a fascinating and moving story that is well written.
Second, it does attempt to address the issue of the causes of poverty for one specific community.
Third, it does provide some insight as to why Trump does appeal to some poor working class whites.

It is for the third reason that the book and the author has attracted considerable attention, although Trump's name never appears in the book.

Vance says in his community the view is:

“We can’t trust the evening news. We can’t trust our politicians. Our universities, the gateway to a better life, are rigged against us. We can’t get jobs. You can’t believe these things and participate meaningfully in society.... There is a lack of agency here—a feeling that you have little control over your life and a willingness to blame everyone but yourself. This is distinct from the larger economic landscape of modern America.”

Nick Aroney brought to my attention a very stimulating review of the book by Joshua Rothman in the New Yorker that focuses on the second issue, particularly that of culture vs. economics. Here is one choice quote.

Americans have tended to answer the question “Why are people poor?” by choosing one of two responses: they can either point to economic forces (globalization, immigration) or blame cultural factors (decaying families, lack of “grit”). These seem like two social-science theories about poverty—two hypotheses, which might be tested empirically—but, in practice, they are more like political fairy tales. As Kelefa Sanneh wrote earlier this year, the choice between these two explanations has long been racialized. Working-class whites are said to be poor because of outsourcing; inner-city blacks are imagined to be holding themselves back with hip-hop. The implicit theory is that culture comes from within, and so can be controlled by individuals and communities, whereas economic structures exert pressures from without, and so are beyond the control of those they affect.

Poverty, economics, and culture are complex and interact subtly with one another. To me it is simplistic to claim that poverty is largely due to either culture OR economics. Yet, that is what political conservatives (such as J.D. Vance) and liberals, both respectively do.