He wasn't fined, he was held civilly liable for damages.

Perhaps the problem is that the fine accrues only to him and his production company; really there were a lot of people involved in spreading lies about Sandy Hook, and their production and distribution. Or that US lawsuits can produce spectacular punitive damages numbers on flimsy justification.

But winning libel suits is really unusual in the US! Here's Sarah Palin losing a lawsuit this year: https://www.bbc.co.uk/news/world-us-canada-60396231