GDP with something actually relevant
Money isn't some purely made-up number we can change at will. It represents real production.
A society with high GDP is a society that produces more value (generally, although GDP can be skewed if you're a tax haven like Ireland). California has a high GDP due to massive economic diversification and control over or a large presence in several critical sectors- like entertainment, consumer technology, industrial agriculture, tourism, finance.
This means California can supply a higher standard of living for itself and for others. Sure, as with the rest of the US, the benefits of this production aren't evenly distributed: some people don't benefit from this massive economy. But the vast majority do.
Much of the rest of the US could simply disappear overnight without really affecting the economic standing of this country. You can't say that about California.
Economics represents reality, and not a reality we can choose to ignore without consequence.
Edited 1/7/2022 19:30:05