I will find a research team made up of the BEST scientists to find me a medication that would allow me to live forever WITHOUT aging or disease. My immune system will be so strong that it can adapt to any virus, parasites, bacteria and kill them or at least survive them. And my cells will be constantly regenerating so its DNA will never be subject to damage, thus no cancer and if I ever get injury, it will self-heal. And each time when I get sick or injured, I will actually get stronger as enabled by this medication. And then I will buy an remote island so remote, so untouched by pollution and so secret that nobody knows it exists and I will go there with ALL the supplies and all my money that I need to survive and just live out my days forever. Whenever I feel like mingling with the rest of the world, I will come down and do some partying and then when I need to I will disappear and retreat to my sanctuary. Since I will never age or never get sick, I don't need doctors. And since nobody knows about this place, I will never get invaded. And if I EVER get invaded, I will buy the best state-of-the-art weapons that will shoot out any incoming enemies. And since I will live FOREVER, I don't really need children, hence no need to mate except the few occasional urges which I can satisfy with my partying in the conventional world. My life will extend FOREVER.
I would buy an airship and travel around the world doing geological surveys and flying the flag for British exports. I would look for buried treasure with my airship metal detector. For instance there is a 17 ton gold hoard in the USA just awaiting someone like me.
Buy a large Tropical island. Build an extensive underground bunker network on the island, LOST style, complete with secret entrances and hidden passages. Buy $10 billion dollars of gold bullion. Bury it somewhere on the island. Build one small cabin on the island and live the rest of my days as a hermit.