Aside from the second part of your comment not making any sense, the entire post shows you didn't read the questions. The question wasn't whether or not SDN represented the whole premed population, but exactly in which way is the sample stratified.
Before you make any condescending comments and give people advice, check your "bogus" assumption that people's curiosity stems from insecurity.
Yes, those with impressive stats do tend to refer to them a lot, but like other people said, there is also a lot of posts seeking reassurance about less-than-stellar numbers. So this self-selected SDN group seems to be distinct in personality rather than in GPA/MCAT numbers. I'm trying to gather some preliminary information for a possible social psychology topic of what kind of people like to go through stressful processes with large network support.