Your information and I.D. gets harvested from a major hack from someplace you do business with, how much can anyone really take from you?

Allegedly Yahoo was hacked big time (about two years ago?) and it was believed millions had their personal information harvested by the hacker. Though it was believed to be state sponsored from another nation, if it were mere thieves, etc. from the nation you reside, what would they get from you? Could they cripple you financially?