Boont; first of all; your You sound like a guy that lost quite a bit of money and is making excuses. /sup] is the reason people don't take you serious. Any good argument will certainly be taken serious.
Then you quote some other people without any comment from yourself.
Then you mention than Greenspan's conundrum is about why increased liquidity does not mean more investments? I believe he used the word in connection with the strange lack of connection between long and short term bonds.
I will give you the benefit of the doubt but....
What is your investment strategy? What are you invested in today? What do you use to get in/out of the market as you did in 2000 so well? Are you retired and live of your investments? Please share a bit more - do not only bring doom-gloom theories but also some solutions (you did mention RE in your defense - anything else?).
As to the subject; over the last 5 years a well diversified portfolio have actually done just fine. The 2000 "crash" was an IT/US large cap "crash" only. The future might however see a more global crash and to have positions beyond the traditional stock/bonds might make very good sense. RE, commodities, precious metals(as a seperate from commodities) Etc.
Also it makes good sense to ensure that one is well diversified currency wise - in the good old days it was easy to stick with home country currencies, but with our more global world, many of our nessesities (not just champagne and German cars
) are made/paid elsewhere before we buy them.
There is also a risk that oil/other commodities might be priced in a basket of currencies in the future - seems to be the trend these days?