If you want to return to the original question of why 76 out of the top 100 YC startups are in the Bay Area and zero of them are in the South, east of LA - it's because the only populations that matter for a tech startup are founders, early adopters, angel investors, venture capitalists, executives who have scaled a company by 100,000x, corporate lawyers, digital marketers, engineers, DevOps/SRE, UX researchers, UI designers, product managers, and (for a B2B startup) enterprise sales reps. All of these populations are abundant in the Bay Area. Many of them are missing entirely in the South, or if they're present, they're rare enough that there isn't a liquid market for them. If you're a founder, you can go wherever you want, but you're only one of the limiting regents for a startup. Without the other, less glamorous ones, your startup is not going to take off.
I think the advantages of the Bay area are overhyped. If you take a look at the of number of people that are employed by these companies, few of them employ more than 500 people. A lot of them employ less than 100 people. I think you can find 100 qualified people to do all of the tasks you need in any US city that has over a million people. VCs and angel investors have to beg great companies to take their money. However, it's best to not need outside investment at all. It's easier to keep the burn rate low if you're in a cheaper city.
It's certainly possible, and I see from your profile that you've put your money where your mouth is. It's interesting that this holds true out of the 100 most valuable YC companies, though. YC has funded close to 3000 companies, which is pretty close to a representative sample, and those companies originate from all over the world. If the Bay Area didn't have a real advantage in growing & scaling companies and it was all hype, I would expect the market to wash it out of this sample.
