first of all the 1 million is a complete estimate and it may actually be a lot less than that.
though there's ever more early miners coming out of the woodwork it was effectively only him for quite a long time. if you were the only miner back then you'd be getting 7200 coins a day. that's one million coins in only 138 days and he certainly carried on for longer than that. i wonder how many people came on board in the early months of 2009. not very many.