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.
He would probably reach that amount that he would be a millionaire but the big question is how did he do that? on what ways does he accumulate such big amount thru donations itself. Well no one really knows what he raise but one things for sure thats a big amount could make him a bitcoin millionaire.