This is a fruitless notion.
The United States isn’t giving up 1500 miles of the West Coast and all the resources of that state just because a bunch of sulky billionaires and left wing snowflakes don’t like the outcome of the election.
It doesn’t matter how many referendums, petitions, meetings, or protest marches are conducted. Unlike EU and BreExit, there is no provision in the US Constitution for a state to secede.
A lot of blood was shed preventing the last group to try it from succeeding. This really is a matter that the Federal government will kill its own citizens over to prevent if necessary. However, it won’t come to that. There will be mass arrests, trials, imprisonment, and martial law.
All those pouty billionaires will become zeros behind bars. No, when threatened, the cowards will flee to some overseas safe haven and leave theIr less financially well off supporters holding the bag. Their arrogance is matched only by their duplicity. Their true allegiance is only to themselves.
There is nothing in the Constitution preventing it, either. The South should have been told, "Good-bye, Good Luck, Wish You Well!" It is that whole freedom thing:
"...That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, — That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness..."
I understand that California is not likely to vote to leave. It would be suicidal for them. My point is that the America I grew up in still exists - outside of California. And if California did want to leave, I'd help them pack...