I am pretty sure that in his wildest dreams he didn't dream that it would get this big. I mean he did assume that "some" people would use it, and he was around when it got a little bit attention as well, but I do not think that he had any idea that it would be this big.
We are talking about something that has peaked at 68k dollars, and we are talking about a trillion dollars in market cap as well, that is quarter or a bit less than the gold marketcap, imagine being gold, exist for thousands of years for payments, from early age bronze/silver/gold coins to now, and then something gets created and in less than 15 years it reaches quarter of your thousand year progress. This is why the fee's are high, because there was no system built in to be ready for something like this.
He knew that if it got attention, it would become very popular. I once saw somewhere in the forum a user had quoted a line from Satoshi where he said that after 10 years or so from now, there will either be a lot of transactions or users or there will be none. I don't remember the exact words but I think that was it. So, it means that he knew, that if Bitcoin starts spreading around, anyone who learns about it will start using it which is why he made that kind of prediction.
I also think that this congestion is not because of normal blockchain transactions because the network isn't this weak to not be able to handle transactions of its users but all these new integrations such as ordinals and stuff, are making a very big mess and normal Bitcoin users are suffering because of it.