I know that Some people buy Bitcoin because they want to store their money somewhere other than a bank. Some buy Bitcoin as an investment, believing that its price a few months or years from now will be substantially higher than it is today. And some people purchase Bitcoin as a means of investing in companies that raise money through an ICO, since equity in those companies cannot be purchased with traditional currency. You can only purchase tokens with Bitcoin or Ether, which is Ethereum's cryptocurrency.
RE: The Primary Difference Between Ethereum And Bitcoin: A Beginner's Guide