Hot take, but it's both. I make $40k in a major american city, and while it sucks I have a decent amount saved up, I live alone, and I've paid off all my debt (although I'll probably never be able to afford a home).
To be clear, I don't think anyone should have to cut the corners I do to live with financial security, and not everyone can (my partner is disabled, financial security is a pipe dream for them), but it isn't impossible for most people.