Maybe your business attracts customers now because they have a lot of discretionary income to spend on it, but if other services that are a higher priority to your users start to find a subscription model to be more valuable than an ad model (because ad blocking is too effective, for example), your customers will have less discretionary income to put to ad-free reading. Further, all of those ad-subsidized reading sites now become your competition.

This isn’t a pro-ads argument, but an appeal to sober, informed debate.