Agree or disagree: marketing is about who wants what you have and has the capacity to pay.

I agree to a certain point. I think marketing is also about reaching new people, who are not necessarily looking for your product or want to buy it. It's not just about connecting with that user who craves your product and can afford it, because stagnation is inevitable. The ideal, to grow exponentially, is to provide value and change people's behavior. Give them a 7-star product/service, often with free samples, and after that they feel stupid not to pay for a subscription or buy it. If you manage to provide something like this, you have no limits, since the number of users grows exponentially.