I'm not agreeing nor disagreeing with you, since Groupon is the only startup I know from Chicago, but Chicago has this same problem with politicians. Pump-'n-Dump. 1 in 5 Illinois state politicians have seen jail time in the past 100 years.[1]

I can't honestly put anything down to words that could describe why, or if it's just coincidence. Just an odd trend.

[1]http://articles.marketwatch.com/2011-12-07/economy/30779893_...