I don't understand what you're trying to say. You can't easily say that asset prices are "disconnected from their fundamentals" - the price is what people are willing to pay for the future earnings of those companies. People are willing to pay a higher premium for those earnings now than they have in the past. Instead of the comparison to historical highs, try looking at developing countries, with lower P/E's and higher interest rates. Yet investors are still willing to pay a premium for US stocks. If you're going to say that the price is wrong, you need to account for that discrepancy. It seems that the argument you want to make is that people buy overvalued US companies because they think everyone else will continue to buy overvalued US companies?