So did Rome at one time.
The problem with California is not its past. That is unquestioned. It is the policies that are being enacted and how it will affect its future.
When you have overregulation making it tough for business to operate, leading to an outflow of capital or a passing up of investment, that will have a major impact.
Unless that state turns things around, it will keep losing major corporations which bring a large number of jobs (along with taxes).
That is how geographic declines take place. We saw it on a city level with Detroit, Dayton, Cleveland, and Baltimore.
With technology today, the migration, from not only states but countries, is never easier.
Capital always flows to where it is treated best.
You have to look at what people want as a whole, and one thing California has is natural beauty, which a ton of people want access to. The beaches, forests, and desert all so close and accessible is one of it's best aspects, driving people to live there. If it was more affordable, I would 100% love to live in California, but alas I just visit. As long as that stays, talented people will head that way, and companies will follow the talent. You see a lot of highly technical people with similar hobbies(rock climbing, hiking, travelling) and a great place for that remains California. I can't think of another place so similar within the United States off the top of my head. As long as those people can afford to live there, tech companies will continue to be based out of there, and keep it growing. You still see so many companies with a large presence in California even if their headquarters aren't there because that's where the talent is.
But after all that, you still have to look at how much remote work is enabling people to live wherever they desire. This is going to be the big catalyst that hurts California more than anything in my eyes. No matter what happens, if I can make the same amount of money while I get to go to multiple different cities and explore things the way I want to, it's the option I'll always take. There's a term for us, Digital Nomads, and it's growing at a global level. My skills are always in desire(you use the internet, networking isn't going away), and when I can do my job without having to be attached to a desk, it's the option I'm going to take. I see investing in a large corporate headquarters as a backwards move these days. Use the best talent from wherever you can find, because if you don't, your competitions will and they'll grow.
I don't think it's going to be just a single state in the US who's going to see this decline, but the country as a whole.
Data privacy laws is the one thing that kind of screws all this. I almost exclusively work for smaller businesses or startups who care less about those kinds of things and will hire someone who knows their things without having to worry about their location.