I'm not 100% sure, but I suspect that once Facebook had about 5-10 universities they were unstoppable. Once you have 5-10 universities, you're going to get all the rest. Once you have all the college students, all you have to do to get HS students is allow them in. And you can get everyone post-college by simply not kicking people off when they graduate.
If only I had realized that at the time, though. I remember thinking that a social network for college students sounded about as exciting as yet another used textbook exchange, but without the revenue.
"... I'm not 100% sure, but I suspect that once Facebook had about 5-10 universities they were unstoppable. Once you have 5-10 universities, you're going to get all the rest. ..."
It wasn't that easy according to "The Facebook Effect" ~ http://www.amazon.com/Facebook-Effect-Inside-Company-Connect... Competitors existed but Facebook had 2 things going for them that the others did not - a) A fast school addition tool allowing Facebook to quickly add new universities & b) A strategic thinking founder who realised if you added universities around existing sites (friends, associates of the target university) you could pull in enough of the users of their competitors sites to render them ineffective. Such is the power of the "social graph" and relentless determination.
That makes a nice narrative but I don't think that the strategy made them unstoppable. MySpace had a huge head start and what happened? They got steamrolled because Facebook had better privacy, better design, better performance, and more features. Facebook's secret sauce is its engineering organization. Sure a lot of good ideas went into it, but lots of companies have good ideas, very few have the technical ability (or the balls) to roll them out as quickly as Facebook has.
If only I had realized that at the time, though. I remember thinking that a social network for college students sounded about as exciting as yet another used textbook exchange, but without the revenue.