A billionaire's investment goals are often noteworthy, but investors should consider their own situation before buying the same stocks.Investors often like to follow the investment advice of billionaires. The moves of such famous investors as Warren Buffett receive significant press coverage and can sometimes be a helpful source of stock ideas.However, investing is not so simple, and Bill Ackman's top two investments serve as an example. In his fund, Pershing Square Capital Management, Ackman invests 36% of ...