I think she nailed it on "Empirically, it seems like the more you need from other people in the startup community (advice, introductions, feedback, funding), the more of a popularity contest it feels like.".

I say this because I live on an opposite environment. I am a solo founder in São Paulo, Brazil. There is a startup scene in here, but as an early one, not as helpful and omnipresent as in Silicon Valley. So when I actually founded my startup I quit it. I quit the events, the meetings, everything. These were either for wantrepreneurs or "lets-congrat-ourselves-how-successfull-founders-we-are" kind of events. I am neither.

So, sure, I have no one to go ask for advice, to talk problems through (that's why I read so much HN and this founder's blog posts). But I also do not have this pressure, this insecurity. I personally also were always very self-confident, don't know why, just knew everything would turn out good on the end. But I do feel a lit bit of this because of my angel investors. They are the ones I want to impress. So I imagine if had this urge to impress not only for the three of them, but for lots of VC investors, fellow founders, mentors, press, etc.

Another difference in the environment that makes my life easier as a founder is that no one here actually expect me to succeed. Sure, my friends and family hope I will get lucky, be a millionaire, etc. But all the time they offer me job opportunities, talk about possible carreers, companies to work. It is not that they expect me to fail, they actually think it is worth a try at being a founder. But they know that probably I will fail and I need to have a plan B, a job.

In Silicon Valley, i imagine a culture where fail ocasionally may be ok, but not quiting. You see this "fail is accepted" everywhere, but actually is ok to fail if you are still trying. You fail a company, if you found another and another, everyone will still have hopes for you to someday succeed. Even the investors of your failed one. But I don't see the same praise if you fail your company and accept a job on Google (or god forbids, a small, humble software company) and tell people you will retire there. Oh no, this failure and quitting will not be accepted. Then you will be a loser.

But here in Brazil is not like that. If I fail this company and try to found another, I will be irresponsible. But if I fail this one and get a good job, i will have succeed. I will be seen as having done a risky thing that could compromise my carreer (founding an startup), but in the end I got a good job, so everything is ok.

As I believe I could get a good job in the end, I feel less the pressure for not to fail and this "impostor syndrome" is not a thing for me.

The doubt is: is the easy going environment bad for my chances to succeed as a founder? Is this meat grinder culture that is SV actually good for its founders? At least the ones that survive it?
I like to think that no, that this is just a negative externality of the real factors that make the difference for SV founders (a lot of mentors, investors, developers, successfull founders, etc.). I like to think that I may be very successfull without the onus of overwhelming peer pressure. But who actually knows?