I can't recall where I read it, but I thought they moved because they didn't see a future in Boston. They thought the VC community just wasn't viable there (which seems like a bet that panned out - not many prominent VCs in Boston compared to their peers).
> We funded the second batch in Silicon Valley. That was a last minute decision. In retrospect I think what pushed me over the edge was going to Foo Camp that fall. The density of startup people in the Bay Area was so much greater than in Boston, and the weather was so nice. I remembered that from living there in the 90s. Plus I didn't want someone else to copy us and describe it as the Y Combinator of Silicon Valley. I wanted YC to be the Y Combinator of Silicon Valley. So doing the winter batch in California seemed like one of those rare cases where the self-indulgent choice and the ambitious one were the same.
> If we'd had enough time to do what we wanted, Y Combinator would have been in Berkeley. That was our favorite part of the Bay Area. But we didn't have time to get a building in Berkeley. We didn't have time to get our own building anywhere. The only way to get enough space in time was to convince Trevor to let us take over part of his (as it then seemed) giant building in Mountain View. Yet again we lucked out, because Mountain View turned out to be the ideal place to put something like YC. But even then we barely made it. The first dinner in California, we had to warn all the founders not to touch the walls, because the paint was still wet. [0]
and, from 2007:
> The idea that startups would do better to move to Silicon Valley is not even a nationalistic one. It's the same thing I say to startups in the US. Y Combinator alternates between coasts every 6 months. Every other funding cycle is in Boston. And even though Boston is the second biggest startup hub in the US (and the world), we tell the startups from those cycles that their best bet is to move to Silicon Valley. If that's true of Boston, it's even more true of every other city. [1]
He goes on in the second essay about why VCs in the valley are more aggressive and more deals get done than in Boston or anywhere else, but I suspect that was a huge part of the reason for the move from Boston
The Social Radars has an episode where they interview PG, covering much of the history of YC: https://www.thesocialradars.com/episodes (second from the bottom).
