Buying something for a dollar and selling it for two is the second oldest business model in the world. Most businesses boil down to one or the other.

Rental property is buy an asset, break it into manageable and consumable chunks (nights, months, or a year of tenancy) and sell those chunks for more than you paid for them.

Airlines buy (or lease) entire airplanes and sell individual seat-routes. They're somewhat less successful at turning a profit than real estate, though.