Warren Buffett beats up on few industries with the regularity of American airlines. In a 2007 investor letter, the Sage of Omaha, still smarting from an errant $358 million investment in US Air two decades earlier, called the sector a "bottomless pit" for capital. He quipped that investors would've been better served if aviation pioneer Orville Wright had been shot down at Kitty Hawk. Now his Berkshire Hathaway is sinking more than $1.3 billion into the four largest U.S. carriers. What gives? It's simple – Buffett's love of competitive moats has trumped his fear of flying.