Here are some of my thoughts…
You say 70% of UC grads are working in CA. Could that be because those grads have always been CA residents?
My kid went to Santa Clara University and graduated in 2010. Amongst her friends, the CA residents are still in CA, and the OOS students didn’t stay in CA. Not one of them (sample of about 20). But all are well employed and are happy where they are. SCU is costly, but our kid and her friends have done very well. Many pursued masters or professional degree programs after their bachelors degrees.