Make no mistake, there is a bubble in early stage companies/financing. What is driving it is the same. runaway demand. This particular bubble is different than the last, because the primary implication of the last has not yet been absorbed. The regulatory structure for raising capitol and 'exiting' has not caught up to a simple reality. New technology displaces old technology faster than regulated exits can be executed. Just look at Groupon. Why do I, as a business, list with groupon, when I can just as easily list with 600 competitors who might be more specialized/niche?
I think there's a strong correlation between the end of the recent Housing Bubble, and the start/ramp-up of all these $Billion tech companies.
I think you're right that rich people need to put their money somewhere, whether that makes this surge in tech valuations a bubble, I'm not sure, I sincerely hope not; but I am fearfull of when the "rich money" starts looking for greener pastures...
If memory serves, the only reason the Housing Bubble happened in the first place was because of the end of the "web 1.0" tech bubble.
Is history repeating itself?
Well Groupon had a pretty obscene private valuation as well. To your point though, aren't pension funds and endowments only taking a small portion, and putting it there for the same reason? Higher potential returns at increased risk? And those return demands are being driven by future payout expectations contrasted with existing returns? Whether you're a multi-millionare or a multi-billion dollar pension fun, getting 1.6% on your money isn't going to cut it.