Because if he had used his huge stash of bitcoin, it would look like a huge premine (around 2 and 3% mined by him, the dev)
Also, the block rewards are supposed to distribute the bitcoin, and not centralize all the bitcoin mined in 1 person hands.
Therefore, i think Satoshi prefered to sacrifice those premined coins for the sake of a better distribution of coins.
i am sure that he is not going to use his large stack of bitcoin and that is not because of what you said. it is because he didn't create bitcoin to make a profit.
you are comparing bitcoin to a random alt(copy)coin with a greedy dev.
and premine is not what you think it is!