California is one of the more difficult states for pre meds.
California produced 6652 applicants last year, but only 17% of them (1147) matriculated at an in-state med school. Another 1559 (24%) matriculated at OOS medical school and all the rest received no acceptances at all.
https://www.aamc.org/media/6016/download
All of the UCs produce large numbers of med school applicants:
UCLA iS THE single largest supplier of med school applicants in the US with 1152 applicants last year.
UCB is #5 in the country with 728 applicants
UCSD is #6 with 621
UCD is #13 with 461
UCI is #30 with 353
UCR is #54 with 246
UCSB is #63 with 211
UCSC, Cal Poly-SLO, CSU-Northridge, CSU-Long Beach also all made AMCAS list.
https://www.aamc.org/media/9636/download
So the picture for California grads interested in med school is that it will be highly competitive no matter where you go for undergrad and it will be even more competitive when it comes time to apply for an instate med school seat.
I agree with all the advice you’ve received above–take med school completely out of your consideration. Pick the school that offers you the best fit and lowest costs.