That would still count as solving a very hard problem for 99% of people.

It's even a hard problem for me, not because I can't set up svn/apache/webdav and whatever, but because I need to actively avoid doing this kind of things and focus on higher order issues.

> Not really... It is not so hard to setup SVN, Apache, WebDAV, and NetDrive, and you got your own Dropbox...

I can't tell if you're being sarcastic or not. The dominant player for an industry isn't always who gets the first implementation (though that's sometimes the case, like eBay), it's often who does it for the masses. Digital music players were common before the iPod, but the iPod made it easy. That's why Rios don't even exist anymore and iPods consistently outsell the bible. Dropbox is easy like the iPod is easy. My mom sees its value.

It's not hard, but not something I need to waste my time on, I got far more important things to do. Therefore Dropbox soved an important problem for me and I'm more than happy to pay them.