The post-2008 economy replaced many middle class, and even upper middle class, jobs with ~$9/hr retail jobs and the gig economy. Both lack sufficient benefits, like health insurance, and the former ensures you never work 40 hours a week because the ACA requires businesses to offer health plans to full time workers.

If you're relatively young and in a metro area, you probably don't see it. Step out into the suburbs or more rural areas, and growth means that there's a new Dollar Tree and it's hiring.