When the game is finished, Robert Space Industries is expecting the Star Citizen game client to be 100GB in size. The company was given $75 million USD from fans over the last two and a half years, and they seem to be using it for content. Individual patches are expected to be in the 2 to 6GB range, but could extend to 20GB if an architecture change requires updating old assets to some new system.
I guess this is a case of “be careful what you wish for”. When you praise a developer for producing a gigantic experience with tonnes of content, it will need to be stored somewhere. At the same time, I wonder when games from typical publishers will match this bar. Say what you like about crowd-funding, but Star Citizen seems to be an example of the business model done right (although their budget is astronomical and that probably helped).
Star Citizen is slowly being released, piece by piece, with a 2016 shipping date.