521 BTC is currently worth about $320,000, and not $1 million.
In a few years he might be Bitcoin millionaire, either with price increase or donations still comming in. If the 500 BTC really come just from donations, that would be impressive. Or he just using one Bitcoin address only (lol), and bought some Bitcoins.
Thats not far to achieve if donations are still coming in. Maybe he is wise enough why people keep on donating. Does he has some charity project? Its not ethical also if he keeps on accepting donations without returning it back to help the needy or community.