I'm curious as to how long would it take some open-source enthusiast to come up with an open-source version of Dropbox-like software that you can install on you

I'm curious as to how long would it take some open-source enthusiast to come up with an open-source version of Dropbox-like software that you can install on your VPS and sync files through your own server. I mean, that would be awesome, but not too profitable.