This article contains some interesting information, including a pretty neat pie chart that kind of supports what I was saying in my original comment.

Satoshi mined a mass majority of the coins while their were very few players out there also mining... A time where the network was at its most vulnerable. He a centralized force on the network ensuring its integrity until the network had spread and sufficiently decentralized.

He was probably cheating the hash power / difficulty adjustment by flicking his hash power power only on around that 10 minute mark so his OP hash power wasn't ripping the difficulty up as other curious cypherpunks and such began running their Bitcoin core with the hashing power of a single ~2008 CPU.

All to secure the network. It wasn't in a trustless state at that time, and he could only trust himself until there was sufficient evidence of decentralization, then he basically stopped altogether.

So, Satoshi mined his coins for no economic purposes. He had a lot of hash power but would only use it around the ~10 minute mark to not disturb the difficulty adjustment to far in his favour that others could not discover blocks. When the network was decentralized, Satoshi stopped mining altogether as his goal was complete.