Satoshi did not premine or instamine the coins.
He "easy mined" them however. This IMO is the biggest bane of Bitcoin, that early adopters got mega payouts, not saying early adopters shouldn't get rewarded but the emission curve for BTC was silly and allowed a handful of people to take the lion's share of the coins, with alot less electricity and hardware investment I might add. If Bitcoin was meant to truly change the world then why is it in only 5 years since its existence do you need a mammoth mining farm to find blocks? There wasn't enough time for the real world to catch up to the technology and for the average "little guy" to get in and start mining and get a decent return. The difficulty rose too high too fast and too many percentage of coins were released out in the wild.