My theory at the time was something I called "The Syndrome" which was based on the idea that the business cycle is based on the balance of "solving problems" vs "creating problems" and thus a homology between the events surrounding 1929, 1968 and 2000.

In the "syndrome theory" there is a crisis of the private sector creating problems faster that can solve them that then leads to a change in the governing philosophy that improves matters for a time, but then we run into the limits of that regime and it happens again.

This theory called the top in 1999 (I remember watching a football game on Christmas day and the ads were for stocks and bonds and not beer and I went home and sold)

In 2005 I thought the 2nd Iraq War would lead to a government crisis (analogous to Vietnam/Watergate) but that didn't happen.

Interestingly there was no real "regime change" after 1999 but instead SOX and other regulatory changes seemed to cement a culture of rent seeking and inpunity.

Milton Keynes, the great trader, said that "Markets can remain irrational longer than you can remain solvent" and that is quite true.