the assertion that the economy is fundamentally different now than it has been in the past, that the current stock market valuation is somehow justified, and that we aren't destined for a depression anytime soon (unlike the history of economic cycles, which would indicate we are due for a correction.

Looking back, it's all so obvious. Basically, "new economy" was a buzzword used to sell the dotcom hype to gullible investors. People were told that since web-based businesses were operating in the new economy, the sensible rules of the old economy that said that companies without a sound business plan will fail and that a high stock price to earnings ratio signifies an artificially inflated stock price that will eventually plummet, did not apply.

This was, of course, a load of bullshit, but the laws of supply and demand dictated that as long as enough people bought into it, it was a smart move to go along with it, even if you knew it was just a short-lived boom, provided you knew when to sell. Of course, this just made the eventual crash even worse.