Also, there is usually a year to claim any prize. So if you find out you have won, just don't claim it until you have had some time to think about it.
We were lucky to win the equivalent of about 15,000 GBP about 15 years ago. It was a contest at a grocery store. They actually announced it over the speakers at the customer service desk the minute it was confirmed, so no anonymity! Of course that is not a life changing event, except in a small way, and for the next few weeks everyone we knew congratulated us.
We still had a mortgage and teenagers at the time, so we put some on the mtg, some away for each child's schooling, gave them a small amount of cash then spent some on our first ever international holiday. Luckily my DH and I have always been on the same wavelength financially, so this was decided quite quickly over a dinner at a nice restaurant.
I can see how some couples or families can come to disagreements over lottery wins, or spend the lot within two years and be back to broke!