Assuming he had some later money (in the Blockchain) that's maybe "just" a few dozen / hundred million worth.

That's plenty money for one person without the liability and the publicity. You can live a life in pure luxury and fulfill all your material wishes.

Maybe he lost the keys or threw away the machine after a year or two. There's nothing to be gained from going public in this case but a massive threat to your life.

Selling this may ruin the story and crash the price. It would probably go against his values and mission. He could easily have other early wallets and have $B's. Most likely explanation though is that it was Hal Finney who passed shortly after Satoshi disappeared.

It's not. Trying to sell it would crash the market.

Still worth a lot, obviously.

That doesn't really answer my question. If you're a modest private person, what can you buy with 20 billion that you actually want, that you can't buy with 300 million?