Don’t be so sure. We have a lot of generally smart people, a huge influx of talented immigrants, media/arts/design, architecture/engineering/construction industry, multiple well-known universities, a growing technology/internet industry downtown, one of the more important ports on the East Coast, biotech and pharma (typically outside the city in NJ, but some companies actually moved back into NY), etc. It’s a far more diverse economy than you’d think, just like San Diego isn’t just squids, sand, and Seaworld 🙂
The decay of the 70s was actually nationwide, but even then NY didn’t have the demographic problems of Detroit (didn’t lose anywhere near 60% of its population).