We're not seeing this type of investor behavior at all right now (please correct me if I'm wrong). I personally am not really sure that FB and Twitter will ever find a way to make huge profits and become sustainable large businesses but looking at the market it's clear that investors share this uncertainty.
And since anecdote is so popular when discussing bubbles, I still don't see "normal" people talking about how they're going to "make it rich!". I had people in 2007 telling me I was missing huge opportunities to get rich in not purchasing a home, house flipping shows were all over tv. In the late 90s I knew HS students that were trading stocks on the school library's computers during lunch.
Don't get me wrong, especially when everyone I know in the non-tech sector is still struggling, I have anxieties that the party won't last. However looking around I see nowhere near the insanity I remember in 1999 and 2007.
[0.]http://www.investopedia.com/features/crashes/crashes8.asp