I don’t see at this time a mental connection between being a former Marine and a C and W bar full of college age students. Probably a nut disenfranchised from society as he saw it.
My guess a life long loser who could not cope with being rejected by the culture so he joined the Marines and was a general discharge eventually and viewed the student group as those who were “chosen” in life. That area and those schools are not inexpensive to attend. Not a racial or religious thing IMO. (shot the girl at the entry gate, why, she was not a threat). Loser.
BTW, I thought this could not happen in a state which has pretty much banned these mags and firearms.
Firearms are not banned in California.