If I were rich, which I presume if I won a lottery, then the thoughts below should apply to a lot of people.
Step 1. Look after number one. Say $2M in investments.
Step 2. Look after relatives, known as 'relos' in Australia. Not so much as cash, but pay down mortgages, student loans. My wife is a Filipina, so the opportunities for 'international aid' are substantial. About 1990, my wife's sister in Manila had appendicitis, so my wife wired A$1000 to pay for the surgery. It felt good to be able to do it. Hint: a National Health Service is a good idea.
Step 3. As Forummm suggested, set up a tax advantaged charitable foundation, and fund worthwhile causes, of which there are many. My favourites are the Fred Hollows foundation which treats cataract blindness in poor countries, and Mercy Ships which moor in a poor part of the world and perform surgery which is unavailable locally. hollows.org.au, and mercyships.org
Step 4. If I won an insane amount of money, and if I were a lot younger, I might buy a marine research ship, rent it out to marine research organisations as a business, and reserve a cabin on board for me.