It makes relatives you never knew come out of the woodwork. Suddenly, everyone believes that you owe them something or that you can fix all of their problems.
It brings crooks and fears of crooks into your life. You become a target for get-rich(er)-quick scam artists and even more hardened criminals. You start to get concerned about the safety of your family as they are now legitimate kidnapping targets. Worse are the legal criminals: banks and investors who will try to convince you of "sure-thing" investments.
You will want to get a lawyer and an accountant, but how do you know that you can trust them? How many stories are out there of people getting swindled by someone who takes all of their money overseas (and often the spouse as well)?
Which leads to the most difficult issue, you stop trusting people as much. Who is only your friend (or your children's friends) because of your wealth? Can you trust your family and friends as you did before?
A prize of that size makes you switch from struggling to get money to being afraid to lose it. It brings a number of issues that most people wouldn't think of to your door. That said, I can't help but agree with Tevye from "Fiddler on the Roof" when he's told that money is a curse: "Then may God smite me with it. And may I never recover."