The problem is much deeper: in the roughly 25 years of WWW we have not really figured out better ways than ads.

In the fourth quarter of 2017, Facebook had 2.2 billion monthly active users, ad rev was 12.779B thus if active users on average paid somehow a little under two dollars a month, it'd be the same. I am not saying, by far, that a flat fee is realistic, I am just showing there's a lot of room for improvement.