Quote from MandelbrotSet:
I'm glad you noticed (even if you didn't comment on it) that I ended my comment with "from a professional".
Taking the opposite side of heavily over sold (during Bear markets) or over bought (during Bull markets) is very tempting to do, and good money can be made if it's just a small percentage of your capital, you manage your risk, and you're really just treating the trade as a one-off and trying to hit a homer.
But it isn't such a great idea when you are trying to get consistent wins. And that's what the pros do, win consistently with small gains by taking high prob bets (ie, with the trend).
Take a look at the financial news ... the end is nowhere near in sight.