GDP says almost nothing about what individuals lives are like, just look at the various petroleum states. As to poor people in the US, it’s basically flat with wage growth or loss depending on how you calculate inflation over the last 40 years.

The median income earners in Q1 1990 made 408$/week, one inflation source puts that at 951.17$/week in Q1 2023, vs 1095$ which is what the actual dividing line was. https://fred.stlouisfed.org/series/LES1252881500Q https://www.usinflationcalculator.com/ Numbers also look different depending on what exact dates are chosen.

However, there’s many ways of calculating inflation many show that hypothetical person worse off. And of course individuals aren’t going to stay at exactly the same income band so many many people really are significantly worse off.