The problem with this approach is that the group most likely to pay to remove ads is also the same group that is most attractive to advertisers. So your pool of

The problem with this approach is that the group most likely to pay to remove ads is also the same group that is most attractive to advertisers. So your pool of users to whom you serve ads is less attractive overall. That means you need to figure out not just how much you make serving those users ads, but also how much you lose by removing them from the ad viewer pool.