Everyone says it's a bubble and yet seven years later, since 2008, I can only think of three major VC implosions off the top of my head: fab.com, zynga, and groupon. Fab was a train-wreck that anyone with a pulse could have seen coming. Zynga... way too dependent on Facebook and a fad. Groupon is the better of the three, only seeing its valuation fall from $30 billion to just $4 billion - but still well over $1 billion. These valuations, as lofty as they seem, ain't goin' lower.