It consists of professional traders (high networth individuals, Institutions ect ) and public.
Professional traders consists of very small percentage of the total count in the market yet they contribute to a quite high (about 40% I guess) market cap. Professional traders employ high caliber of stock analysts,get insider information and do stock trading for living.
On the contrast public consists of larger percentage of total count (more than 95%) and contribute to a about 60% of market cap. Public trade rather casually and trading is not their means of living.
Professional traders always has the edge.They manipulate the market and make the price high and sell at the peak. To do this they use all kind of propaganda. Use newspapers, forums, and any kind of means. after they sold their shares they produce another rumor or news articles and let the price go down. after making the price down and collect enough at the lower level again start a rally. In the second time they may not be playing with same set of people. Professional traders may not win all the time but they win at least 90% of the time.
So it is the public loosing most of the time. I think 90% of the public looses. Some quit and new set of people arrives and the story goes on.
All joining new wants to be the wining 10% but few succeeds.
If you can invest and monitor price for few years you get quite a good chance to get reasonable return (more than fixed deposits). Here also need to be careful not to buy at the peak.
if you are going to play the game with professional traders (Insider traders) you should know that you are at a very big disadvantage. You may win but the probability is very less.