For reference, compare the following two editions of a book regarding the recent housing bubble. These were written by the chief economist for the National Association of Realtors at the time, David Lereah.
Original title (2005):
http://www.amazon.com/Are-Missing-Real-Estate-Boom/dp/038551...
"Updated" title (2006):
http://www.amazon.com/Real-Estate-Boom-Will-Bust/dp/03855143...
I think we all know what happened next.
When people start spewing denial, it's time to think about heading for the exits.
One can invest in Bitcoin if one wants, but only because The Market Can Remain Irrational Longer Than You Can Remain Solvent