Being an altcoin that is a fork of a fork off Bitcoin, Dash is a minable cryptocurrency. This is an alternative to buying the coin at crypto exchanges.
Mining cryptocurrency requires that you always have a mining software running, and while the software is free, the electricity to run the computer is not. It can also take a long time before you mine enough to earn a coin. Those who mine crypto for a living typically own server farms, which consume a lot of electricity. For the average user, buying Dash is the easier way.