I'm loving this sequence of events just for opportunity to see the cognitive dissonance of some HN commenters in action.
The FB IPO strategy was to wait for the peak (or "plateau", if you prefer) in their growth, collect money from the public and then, for the insiders, quickly cash out.
As for why they wanted to collect money from the public through an IPO, we can call it greed, but truthfully it was also the logical thing to do for the company. They knew were not going to grow revenues any further from the Facebook "business model". Revenues would slowly decline going forward. The novelty factor would disappear and advertisers would learn. But with an IPO they could bring in many years worth of revenue, by selling worthless shares to gullible investors, and extend the life of "Facebook Corporation". As long as Facebook has cash, they can stay "in the game". Like Microsoft, they do not need to innovate, they can just acquire or copy new players as they come along. They just sit and wait for the competition to arise, then quickly snuff it out, with cash.
New ideas and innovation are what can kill a company like Facebook (or Yahoo, or Microsoft, or so many others). The way you stay in the game is by having the cash to purchase the work of the innovators who would otherwise render your business obsolete.