I'd probably buy myself a small home, set aside a bit of money in a bank somewhere with a cash limit, save a little bit extra to commission art or to learn a skill somewhere. This would be barely a dent in the 7 billion; probably 1 million at most, give or take half. If I had that much money, I assume my friends and family would want some, so I'd probably pay a little bit to help them out if they wanted it. I'd also like to travel to see friends I met on Pure.
I would then split up the rest of the nearly 7 billion dollars and give it to various charities. Giving it all to one charity I feel would put too much pressure on that charity and have diminishing returns, so I'd rather donate to as many places as possible to ensure that as much good can be done with the money as possible. I don't want to keep any of the remainder besides emergency savings.
I would prefer to get rid of the 7 billion as soon as possible; I feel like holding onto that much money would cause me to morally decay, and also result in long term unhappiness. If I was a billionaire, I would have problems trusting friends, constantly thinking that I'm only valued for the money I'd have rather than for anything good about myself. I'd distance myself from others, and I'd be less able to connect with people as I'd have lost perspective on what it means to be an average person. That sounds like a lonely experience I'd rather not have, so I could not see me being rich long term at all. I don't want my value as a person to be an arbitrary number.