I do live in Silicon Valley and they most definitely do exist. More importantly though is that the scene in Silicon Valley is dominated by a single type of person - male programmers. Part of this culture is bro-tastic. Part of it is geeky. Most of it is some weird munging of the two where two guys might be comparing their ePeen, their ninja-hacking skills or their lift reps. Overall it is offputting to diversity which is the real problem.