Buy large property, create an anarchist commune, build Earthships and similar housing out of sustainable recycled material, setup public gathering spaces, spa areas, perhaps stuff like rooms for artists, musicians, workshops, etc. Grow weed, shrooms and veggies, have some animals living in relative freedom and perfect health.
Ensure everything is weather proof based on location's projected future climate, build water/heating/energy infrastructure (solar, wind), offer each building as rent-to-buy, keep growing the community and make sure to plan for the day the government gets scared and sends in their death squads.
Basically something like Kristiania in Copenhagen but bigger and more focused on sustainability and land mass, so probably outside of major cities.
Addendum: Would be a good idea to make it impossible to have this grown into an insane religious cult though. 🌚
As cool as Earthships sound, I feel like they aren't a good fit for all climates. I'm in Canada, and unless you live in BC (and I'm talking Vancouver or the island), your only sustainable building option is straw bale.
Even if I could go further south to a more temperate climate, part of my fear is that anything south will get unbearable soon. Even Europe is going to be hot as hell.
I should add that I'd also take care of the more self-centered stuff like taking making sure my me and my girlfriend/*, parents and brother won't have to work a day in ours lives (unless we fuck it up but I'd try to find someone capable and trustworthy who would take care of it).
/* and since I'd never want her to feel captive I'd make sure all paperwork was done to allow her to walk with her money anytime, no matter what.