Investors buy stocks in order to sell them at a profit in the future

Investors buy stocks for a number of reasons, many of which are ill-advised. 

From purely an investment perspective, there are only 2 reasons to buy common stocks.

1.  True equities investing consist of identifying those companies with stocks undervalued in terms of future earning power and buying them now because the projected earnings per share (EPS) stream is expected to produce dividends.  So the first objective is dividend income. 

2.  The second objective is capital appreciation.  Growth in price tends to occur over time

• if the fortunes (fundamentals) of the underlying company improve,
• if interest rates do not move sharply higher (squeezing price/earnings ratio [P/Es], and
• if market psychology moves from negative to neutral or positive.

To be successful a transaction requires both buying and selling, since both are required before a transaction's final result is established. 

Many published books dealing with stock market investing in any form focus overwhelmingly on the buying transaction only and neglect the sell side of the equation almost completely. 

Selling may not be exciting, and assuredly it is a narrower topic, but it is absolutely necessary and has its own very interesting twists and curiosities.