US economic growth is much much lower than it was 50 or 70 years ago. Population growth is also lower. If we're pointing out modern issues like the rich getting richer then I feel the correlation is with LOWER economic growth causing it rather than HIGHER economic growth. Once it becomes closer to a zero-sum game the rich have an advantage. Ecological damage goes the other way since it's harder to grow quickly with environmental restrictions.
This really depends on how you look at it. On an absolute inflation-adjusted dollars-per-person-per-year basis, rather than a relative / percentage basis, GDP growth over the last decade has been substantially higher than that of the 1950s. Even 2% of $55,000 is still greater than 7% of $15,000... https://fred.stlouisfed.org/series/NYGDPPCAPKDUSA
