For a store with a design aesthetic that feels impossibly modern, it's hard to imagine IKEA existing right around when gingham kitchens came into style. But Ingvar Kamprad who was just 17-years-old at the time, launched IKEA as mail-order sales business that originally only sold small items, like picture frames. Now he's 89 and worth $3.4 billion. Not-so-fun fact: Kampard was actually a Nazi sympathizer in his youth. But he calls that period "the greatest mistake of my life," and even wrote a letter to employees asking them to forgive him.