"Buy the rumour, Sell the news" is actually meaning to buy on the expectation and research you have done with the consideration of "Forward PE ratio". When the stock price have gone up to your target price, you should sell and take profit

This profit gain is to reward to the investors who have putting effort to do fact finds and research. 

"Buy on rumors, sell on news" is a well-known investment strategy that suggests that investors should buy stocks based on rumors or speculation and then sell them once the news is officially announced. The idea behind this strategy is that rumors and speculation can create market hype and increase demand for a particular stock, leading to a temporary increase in its price. Once the news is confirmed, the price may drop as the hype fades and investors begin to realize the true value of the stock.

This strategy is often used by short-term traders who aim to profit from short-term price fluctuations in the market. However, it's important to note that this strategy is not foolproof, and there are risks involved. Rumors and speculation can sometimes turn out to be false, and news events may not always have the expected impact on stock prices. Therefore, investors should always do their own research and analysis before making any investment decisions.