Jack Durish's answer to Would California be better or worse off as a sovereign nation? - Quora

YES.
Ten reasons why it would solve a bunch of problems for them.
1. No longer having to educate the rest of the nation about Pew-Pews.
2. No longer having the USA telling them how to use Federal Funds to fix their Infrastructure (Only highway sound-deadening walls between affluence neighborhoods are the only important walls).
3. Being able to support their own Sanctuary Cities without worrying about ICE. (Put some walls around them keep'm in and protect rich people outside)
4. Not having their Constitutes seeing photos posted of their homeless living underneath the highways across the state.
5. Not having to worry about Northern California (since they would withdraw from California).
6. No need to worry about the Central East counties of Alpine, Toulumne, Mariposa, Madera or Inyo Counties since they have always formed a political block against the California West-Coast Cities, as they probably would want their own statehood (so selfish of them).
7. Or those pesky San Bernardino, San Diego, and Imperial Counties with all their US Military Forts, Marine Camps, Air Force and Naval Bases - which would remain in US hands.
8. San Benito, Kings, San Luis Obispo and Kern Counties would most likely would be completely forgotten about by the 'New California' (no change there) and no one would notice as they remained in the USA too.
9. Sacromento would of course rule over San Francisco, Oakland and San Jose.
10. The Los Angles Basin would do what they always do, ignoring eevryone else while they wait for the 'Big One'.
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Lots of opportunity here for the other five regions of California to get from out of Hollywood's glow to develop their own lifestyles.
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On the other hand, all would lose their status as states to become territories of the USA, where their governors would be appointed by the US President.
Win-Win

Purely hypothetical, as secession is Unconstitutional.
But no, more would be lost than gained if California was its own nation.