Ultimately he wants all users to be paying users.
Louis Rossman has stated in a few of his Youtube videos that he would make more money if you sent him $1.00 than if you watched adds in a years worth of videos. I don't imagine that Twitter or Reddit are any better.
I think that what we're actually seeing is the death of advertising supported services. There's just not enough money in adds to be viable and there's no more free investor money to burn.