2. Founder ponying up millions of his own cash.
3. Frighteningly Ambitious(TM) problem.
4. Reasonably good traction and product execution.
So it becomes a complain and explain platform like twitter.
5. Investors are hunting for an Instagram-like Facebook spillover win.
Its possible that they launched as a general purpose Q&A site and then they may have switched when it seemed prudent. Or its possible that they may still be trying to be a general purpose Q&A site, but in that case their branding doesnt match their ambition.
I don't know a single person outside the (somewhat incestuous) startup industry that uses Quora. In fact, I do not know a single person outside the tech industry who knows about Quora.
Claims that Quora has achieved good traction are, to be polite, overly generous, but more frankly, bullshit.
Also: they have an interesting strategy of courting mainstream media distribution; there's a "Quora" section on Slate now, for instance. They could keep doing that.
9 figure valuation? No clue. Valley numbers, agreed. Just saying.
This would not mean much in general, but I am willing to bet that most of those Quora investors are also Quora users so they suffer the delusion too.
Sure, Adam D'Angelo and Charlie Cheever didn't actually start Facebook, but they came as close as anyone can be short of actually being Mark Zuckerberg.