Which is probably the point. If I had a million coins, there's no way in hell I would just give them away and neither would you, but it's bad for the supposedly decentralized Bitcoin in general, when one person/entity holds almost 10% of the entire supply and thus has the power to kill it for years.
If I'm doing my math right, miners will mine what Satoshi allegedly holds in 278 days. His share drops from 10% to 9%. His power to "kill" bitcoin will degrade over time.
No, the rate of new Bitcoins degrades exponentially. Even at the maximum limit of 21 million Bitcoins, Satoshi would still hold almost 5% of the entire supply a hundred years from now. Still way too much.
That is a good point. However, the fear is that Satoshi would commit a irrational malicious act against bitcoin at no or little personal gain for him/herself. Unlikely, but a concern. Currently, that 1MBTC isn't worth anywhere near the spot price if suddenly converted to fiat (because the markets aren't big enough), he/she has a while to wait before using it to buy the private island and the fleet of yachts -- or spending it on eradicating some horrible disease from the planet. It is much more likely to be sold off as needed, as the price goes up, without crashing the market.
As I understand it, the richest person in the USA, Bill Gates, cannot convert the majority of his wealth to fiat money or anything else. Most of his wealth is in Microsoft stock, and he is legally constrained to the amount of Microsoft stock he can sell, such that he couldn't sell it all before dying naturally from old age.
Sorry to say but your wrong, Bill Gates can sell/give away all of his shares for their prices' worth in Fiat assuming they're buyers...He's not legally constrained so that he can't sell it all before dying of all old age..