Curious about California if it were to secede

Economy of California is the largest in the United States, boasting a $2.746 trillion-ish GPD. It ranks 5th in the worlds largest economy. Some say it can manage itself without the rest of the US. Can it really?

Because of those horrendous fire outbreaks across Cali, it needed President Tump to sign this so-called Major Disaster Declaration. A Major Disaster Declaration provides funds to affected communities for a wide range of support. This includes crisis counseling, housing and unemployment assistance and legal services. This belongs to the federal fund.

If California were to secede, it would get none of that, no? I'm curious how it could survive or handle the situation in this case. Even the rich like the Kardashians were able to hire 'private' firefighters.