It's true. Take Michigan and Detroit. Up through the 60's both were Republican run. Then the Democrats started taking over. After the 60's both Michigan and Detroit were almost solidly Democrat run. The economy tanked. The auto industry fled the state and manufacturing there went into a steep decline. Taxes rose precipitously. Government brought in programs like LBJ's Great Society and the decline increased in speed. Today, Michigan is a shadow of its former glory, a shell of what it once was.
California is no different. Up through about the same time period it was Republican. It was the leading state for industry, manufacturing, and business of all sorts. Then the Democrats got solid control and began to run the state into a ditch. The manufacturing and industry left due to high taxes and burdensome government regulation. As the Democrats increased taxes and regulation, other business sectors followed manufacturing and left the state. Now the farmers are leaving due to heavy handed environmental regulation. The middle class and many of the rich are leaving to avoid high taxes and an unaffordable cost of living.
California isn't completely finished, yet. I figure it's got another 20-ish years to go to reach the point where it becomes the next Michigan / Detroit.
States like Texas, North Carolina, Arizona, and Florida are on the rise. They are becoming the next round of successful states. Then, at some point, the Democrats will get control and drive them too into a ditch. It's already starting to happen here in Arizona. Tucson, for example, has become the "Berkeley" of Arizona. A Progressive Leftist university town that is wondering why they can't attract companies with lots of high paying jobs as the streets turn into potholed hell and the anti-car local politicians wonder why there's traffic gridlock everywhere in their city.
Democrats / the Left--one in the same thing now--always fuck society and the economy up where they get in charge. They hate individualism and see success as evil.