Sorry, but the U.S. economy is a $14 trillion economy. Anyone who says we're in a bubble based on the aggregate Silicon Valley venture capital funding in the last year is getting ahead of themselves. Before you lecture us on a bubble, try to understand some basics on the U.S. economy.
I am commenting from the perspective of someone who is not in the US. Currently from the Asian region (excluding China), valuations are no where near that of the US. In Singapore alone, even with for a startup with vast customer based overseas is being acquired for only $10million. Yet, that $10million acquisition is more than enough to make the startup a superstar in our ecosystem.
Perhaps this bubble is only present in the states, but elsewhere in the world, valuations are still reasonable.