If money were no object, many of us might fix up an old car or remodel the house. Millionaires and billionaires use their fortunes to build spaceships, pursue immortality, create island nations, or mine asteroids. Then there's Tesla founder Elon Musk, who is once again looking to buy Twitter for $44 billion after spending months trying to back out of the deal. And that's not all. The world's richest man took to Twitter to promote his new perfume, named Burnt Hair, which doesn't sound Musk-y at all. Perfume aside, many eccentric projects of the rich tilt toward serious subjects, such as advancing science and environmental efforts, especially in the oceans, or travel in outer space.