I'm actually not usually as active in the Plaza once I hit 999, but to answer your question, even I'm not fully sure. I think part of it is that I just like the communication features and seeing everyone else's avatars. Also, there's going to be a global mission that involves spending as many FC as possible. I'm gonna aim for a contribution of at least 250,000 FC. I currently have about 200K even on me atm.