If I had to guess as a lifelong California resident, I'd say the salary discrepancy is probably the biggest factor. I'd also guess the weather and lack of available jobs would be the next biggest factors, not necessarily in that order.
Yep, tech peeps loving in Cana want to work in Cali, not so much the other way around, in my experience, not so much the other way around.
No, imagine the salary potential, not the discrepancy. Ape stronger together. We'd be a new world super power