So if you think that everyone to date is wrong and that there really is money in it--why aren't you doing it yourself? If you think it's a lack of "balls" keeping others from catering to your niche, do it yourself. But rather, I think that you're not giving people enough credit. Why would they cater to
you when they can cater to people with lesser expectations and freer, larger-in-aggregate wallets?
It's not that there isn't a market. It's that that market is very high-maintenance and, if you look at other similar products, probably extremely difficult to effectively monetize. Targeting users who come with the twin attributes of being touchy and quick to leave and are probably unresponsive to advertising and other straightforward "you don't pay" models does not strike me as a brilliant decision. The success stories in the described niche--Tarsnap comes to mind--seem mostly to be very small businesses or strange attempts at capturing the zeitgeist a la App.net. (Tarsnap being a small business isn't an inherent negative; I personally have little use for the "startup startup startup, business plans optional" silliness that seems to be infecting the tech sector and cperciva has built a great product. But you're not complaining about Dropbox, you're complaining about Quora and Facebook, which have very different business needs.)
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Or, put another, admittedly more cynical way: I don't know many people who want to cater to a market segment that will hate them as soon as they start needing to find ways to make payroll. Some people price themselves into or out of a market segment. You behave yourself out of what have heretofore been economically viable ones. Which is totally fine if that's your bag, but following that up with complaints that people who want to make money aren't interested in catering you is...curious.
There are generally easier ways to make money than to build low-barrier-to-departure services for demanding, temperamental people. So it goes.