Doesn't seem like a valid hypothesis. Programming computers was originally predominantly done by women, remember, so why is SV mostly white guys? We've already seen both genders can do the work. I've worked with lots of women at hackathons and know some who went through coding camps and landed software engineering jobs at places like Etsy, so know they aren't excluded because they "can't do the job best" like you imply.

If some white guys with money thought other white guys with money do the work best, and made sure to hire other white guys, don't you feel like that's discrimination? Why would a claim that it "just happened" mean it isn't discrimination? I've definitely seen this happen at lots of startups I've worked at. I knew a Princeton C-level from a top 10 app company who would always only hire people from the same school that pretty much looked like exact clones of him.

Similarly, at work, I've had directors agree to let me work on big, ground breaking projects, but as soon as they see I'm disabled they immediately change their tune from a transfer being "one easy email" to "oh, we changed our mind, deal with it, don't talk to me, talk to HR".