From someone I follow and respect. I could not say it any better.
"Valuations are at a level where reversion to mean would cause about a 40%
decline in the S&P 500.
I think the situation today is more akin to 2000 (but it could be 1998; don'
t know how much further the run up will go) than 2008. That is, equities
are already at unsustainably high valuations, but the underlying economic
fundamentals aren't too bad.
2008 was a situation where we could have ended up in a catastrophic
depression if policymakers reacted poorly. The current situation is more
likely to end up in a run-of-the-mill equity bear market. I'm willing to
take temporary losses in that kind of situation. The presumption is that
focusing on areas of relative value & countercyclical names will mean market
losses will be steeper than losses in my own portfolio, and I will be able
to take advantage of any opportunities that arise. In addition, if the
market continues higher into bubble territory, I'm positioned in such a way
that I don't think I'll lag behind big time (even if I do, I don't worry too
much about lagging behind in a bubble). "