&gt;if you know a company well and you know they are doing great and will be doing great in the next year you should buy their stock<p>This is a truthy-sounding and extremely common belief about the stock market, but false. Buying stock is <i>not</i> a bet that the company will do well, it&#x27;s a bet that the company will do <i>better</i> than other market participants currently think it will.