''Distributed by the University of Nebraska Press for Caxton Press''''When everybody thinks alike, everyone is likely to be wrong.'' The ten words quoted above are, according to Humphrey B. Neill, a potent factor behind the economic booms and busts that blight our civilization. The ''Mississippi Bubble,'' Holland's incredible ''Tulipmania'' and the New York stock market crash of 1929 are historic examples of disasters magnified and hastened by the pressure of mass opinion. Neill describes these occurrences in detail and tells the reader how to avoid and recognize the dangers that ''following the pack'' can pose to the discerning investor.