If you host a business on the domain that makes a lot of money, sure, go ahead and get the domain. But if you are currently thinking about creating a start-up without concrete plans how to turn a tidy profit? Then no, you have bigger challenges than which domain to use.
My suggestion: get a dirt cheap domain with 8 to 12 random letters, build the site, and once you have a couple of (paying!) customers, then worry about the domain and move to a nicer one.