That doesn't follow. If they had one reader, who paid them a million dollars per year, then they'd still be in business. So, if they had a million users, who paid them one dollar per year, they MIGHT be in business because it would cost a lot more to deliver to a million people than to one person.

By throwing up the ad blocker wall they're saving the cost of serving anything more than an ad blocker wall to the people who aren't paying them. Sure, they're limiting their audience, but they're limiting themselves to a PAYING audience.

The people who are willing to pay them might change their minds in the future, but their decision won't have anything to do with the unknown number of people bouncing off of the ad blocker wall.