If he knew already that bitcoin would become a hit in the future, then leaving the bitcointalk forum and staying anonymous from then until now serve its purpose. Bitcoin is making its way to its global adoption which increases year by year, and for that, bitcoin becomes a threat to the government and traditional banking systems knowing it offers alternative system for transactions and store of value without the approval of the bank or the government itself. If Satoshi remains visible at the moment, his safety and security will definitely be at risk. Good thing he’s not.
Satoshi Nakamoto did not know too much about future. He built up Bitcoin project, was part of the community and when the founder saw that the Bitcoin community were big and strong enough, he decided to disappear. As the founder, I believe that he actually had strong belief in success of Bitcoin, but it's not like he knew everything about future before the disappearance years ago.
I'm sure that in 20 years there will either be very large transaction volume or no volume.
I can say the same too and it won't be wrong with two opposite options for future.