The last few years of a bull market are always a bit of a mystery to professional investors; the market rises faster than it did in the early, cautious years when nobody believed there WAS a bull market, even though there appear to be fewer fundamental or economic reasons for it. The current bull market churns on, even if nobody can explain it, and people who bail out in anticipation of a downturn do so at the risk of missing out on an untold number of months or years of (still somewhat inexplicable) gains.