They basically decided they didn't want to pay for society anymore because we gave the blacks civil rights in the 60s and the end of school segregation. Hence the tax revolts of the 70s and Reagan in the 80s.

When did all the problems in our infrastructure, education, and health care start becoming noticeable? The 90s...

Even at the local level, you can see how much zoning increase in the same time period as a way to keep the blacks and other undesirables out. It's racism and classism all the way down. Nobody wants a 'great society unless it's exclusively white and wealthy.