Traders and investors play a very important role in the stock market, Investing is like planting an orange tree , you put money into the stock and over time you expect to price of the stock to go up while producing dividends each year.
Trading is equivalent to running a lemonade stand- buy and sell stocks quickly, by taking advantage of short term price fluctuation. Both Investors and trades can make money in the stock market but trading involves much more risk due to time, commissions and volatility.
Investors tend to focus on the long term potentials of the company stock and let the stock gradually rise or fall a lot. The Cons of investing is when a position is losing money, not sleeping well at night becomes an issue due to worry.