what is in it for someone—what advantage or benefit can a person receive from smth.:
- He had an inbred suspicion of any kind of offered help, he wanted to know why people were giving it, what was in it for them.
what is it to someone—what business is that of mine, yours, etc.; does it concern me, you, etc.:
- Now why does that thought gnaw at me? What is it to me if he does not pay more attention to me?