Over the past few weeks, Warren Buffett has been buying shares of Occidental Petroleum Co. NYSE: OXY to bring his net stake up to 29%, which is not Buffett's usual behavior. When the Oracle of Omaha invests this heavily—and this quickly—in a stock, there must be a good enough reason to justify these quick and aggressive decisions.While there is enough evidence to back up a bullish rotation in the energy sector, what investors need to know today is that they must not let fear of missing out (FOMO) drive thei ...