"Equating investment, or return on investment of capital, as a barometer of "success" ... is a first issue"
No, ROI is a great measure of 'success' for an institution like YC, in fact probably the best individual metric.
" It is a perfect case in point as to where and how discriminatory practice gains a foothold"
Or it could be the opposite of that: a place where people are mostly free of ideological assumptions and discrimination.
"absolutely littered with male white dudes and a dearth of sociologists is a perfect echo chamber."
Making such an assumption is 'actual' bigotry, not 'possible discrimination' because the statement devalues the opinions of those making comments essentially on the basis of their gender etc..
Personally, I'm perfectly open to nuanced ideas on how all of this should work out. I definitely think there is work to be done, and we can be more thoughtful about all of this ... but I find so many of the SJW arguments are 'hammers' from the 1960's, like 'unequal outcomes = sexism'. Those arguments are having less and less validity. We need nuance and dispassion on the issue.