Put $20MM in urban and semi-urban property (a few nice complexes in SD would work fine), conservatively yielding 4-5% p/a. That’s $800k to $1MM per year. Spend another few mil on some decent farmland to have somewhere to go in case of a zombie apocalypse.

Do whatever you want with the other $350 mil or so after taxes. Start a charitable foundation. Go to grad school and go into research. Travel the world. Fast cars. Slow sailing yachts. Harlots and cocaine. Whatever floats your boat, just as long as you’re set with enough income to be comfy for life.