To start off, I'm very green in my understanding about finance or the behavior of the stock market, but it does seem to me to be driven largely by fears & emotions of investors. If investors feel optimistic, they'll buy more stock, and on aggregate, this behavior drives up the market. The opposite happens when investors are fearful of the future or of shrinking stock values.

Given this, I have (I'm sure) a stupid question. As it relates to the stock market, why can't we create a mutually agreed-upon pact that we'll all be optimistic about the future, not sell our stocks, and watch the market climb in happy merriment? 

I realize that in a free market we can't *force* anyone to hold onto stocks or sell them. But another way to ask my question might be: **why can't we create a self-fulfilling prophecy of optimism in the market, thus benefiting everyone with investments in the stock market?** If we're all optimistic about the market's prospects (or at least act like it), doesn't everyone benefit? Who wins when we're scared of the future?