Dreman in his book, "Psychology & the Stockmarket" says:
The best chance an investor has is to stand apart from popular thinking. He must be willing to forego the thrill of being in unison with the market, in agreement with the expert opinions and with the exciting, seemingly surefire ideas currently in vogue.
This is no small sacrifice. To own the right stocks in a rising market is a heady experience. There is a wonderful blend of monetary gain and ego satisfaction in being right in a popular manner.
Man is a social animal. To succeed, the investor has to be able to withstand the tremendous pressure leading to conformity. He will face a continuing flow of negative feedback from the market, from experts and from groups of people whom he respects.
The reader may feel a little bit like the patient whose doctor has advised him to give up sex for his health.
Some of us might just prefer to die happy.
The above excerpt simply means that to succeed in the stock market, one must be able to avoid the herd instinct, have full confidence in oneself and act without referring to any one.