The big reason to buy Altria's (MO 1.77%) stock is its lofty 6.9% dividend yield. For comparison, stocks in the S&P 500 are only yielding an average of 1.3% and the average consumer staples stock's yield is just 2.5%, or so.But is Altria's huge yield enough to make the stock worth buying? Read this before you jump aboard.What does Altria do?Altria's primary business is selling nicotine products, with cigarettes making up the lion's share of its revenue. Although hardly a life necessity, nicotine has addicti ...