I'd buy a nice house somewhere a bit wild and in the middle of nowhere on the south coast of either England or Wales, something old with character and a big garden with a good pub nearby. I'd also buy a classic wooden sailing yacht and put enough funds aside to maintain her as well as kitting her out for serious passage-making. When I'd done that I'd figure out how much money I need to make work optional for the rest of my life and how much would keep my family comfortable in an emergency, as well as a small 'shit hits the fan' fund kept in something you don't need electricity to access like gold just in case. I'd then donate the rest to charity, the bulk to enviromentalist lobby groups and charities directly helping people (the RNLI comes to mind for example) but also to a few niche causes like keeping the ailing pirate radio ship Ross Revenge afloat and starting a breeding programme to save the highly endangered otterhound. I'd also like to have a few documentaries made, and I'd drop a few content creators I like some donations too.

Honestly all I really want to do is go sailing and not have to deal with the rat race, I don't want to live an oligarch's lifestyle and I definitely don't want the sort of attention and arseache that money would bring you. That money would be far more effectively used for good in the hands of others so I'd end up donating the majority of it, I suspect on the order of 80% of it at least.