Hard-earned money, rest, or success is something you got only after a lot of work. People use it to show respect: this was not luck and not a gift. Parents talk about hard-earned savings; a team talks about a hard-earned win. It is everyday English, a little warm, and it almost always sits in front of a noun (hard-earned cash, a hard-earned break). Though actually you can stretch it a little — even a quiet afternoon can be called hard-earned if the week before it was brutal.