I got into Cal, UCLA and UCSD as a philosophy major, is it foolish to choose UCSD?

Not sure about UCSD/UCLA’s philosophy departments, but Cal’s is known for a super heavy emphasis on analytical philosophy (https://en.wikipedia.org/wiki/Analytic_philosophy). This means that a substantial amount of time is spent on formal logic, that is, the psuedo-mathematical formulation of arguments.

See some examples here: https://plato.stanford.edu/entries/analysis/s6.html

So you won’t be sitting around chatting about Kant’s Categorical Imperative or reading Plato’s Republic. It’s great prep for the LSAT though.