I wonder why this was downvoted? I think the point is obvious: if you suspect that founders, employees or investors regard their company's IPO as any kind of finish line, then you should run away from that company. Here on Hacker News there have been many stories about companies doing badly once founders cash out. And we have read many stories about the negative signal that it sends. I thought this was common sense, and so I didn't see a need to post any links, but it is trivially easy to find articles on this subject:

If Groupon were such a great business, why have the founders cashed out in each of the investment rounds?

http://www.quora.com/If-Groupon-were-such-a-great-business-w...

"But even beyond the lockup, a founder selling a significant chunk of equity can send a negative signal to the market and erode confidence."

http://www.rudebaguette.com/2012/05/22/going-public-its-comp...

"Zynga’s Mark Pincus is promising in an open letter to potential shareholders that his company will be a 'meritocracy'. Except that in his meritocracy, Pincus has created a class of stock just for himself. He’ll have 70 votes for every supershare of Zynga he owns."

http://www.thedailybeast.com/articles/2011/12/14/zynga-s-ipo...

Do a search on Google and you'll see a thousand articles like this, all with the same theme: when insiders sell, you should run.