Of one thing be certain: if a CEO is enthused about a particularly foolish acquisition, both his internal staff and his outside advisors will come up with whatever projections are needed to justify his stance. Only in fairy tales are emperors told that they are naked.
The (stock) market is there only as a reference point to see if anybody is offering to do anything foolish. When we invest in stocks, we invest in businesses.
Investors making purchases in an overheated market need to recognize that it may often take an extended period for the value of even an outstanding company to catch up with the price they paid.
If we start deciding, based on guesses or emotions, whether we will or won't participate in a business where we should have some long run edge, we're in trouble.