If it makes them feel any better, I told people in the 90s that the WWW didn't make sense because we already have telnet, archie, gopher, veronica, and ftp. What can WWW give me when I already have those tools to connect with...
In this case, Gopher was a ticking time bomb, as the University of Minnesota was looking to charge money for the server implementation. Tim Berners-Lee was adamant about keeping WWW open and got CERN to agree to release it as public domain. Dropbox has a similar advantage, at least for me: it's not tied to a particular OS vendor or office suite. I can run it on basically anything and have first-class access to all of my files.
