No. For many of us it irrelevant if there is duopoly in the ad space because we don't use Facebook and we use ad-blockers. But in the payment space VISA/MC charge high fees which are passed onto all consumers.
Products that you buy have their marketing priced in. Even if you don't see the adds you are still paying for them.
Marketing costs are not included in Gross Profit Margin calculations, and don't have an impact on COGS.
Marketing spend is primarily used to grow your TAM and channel customers to your product, but is very marginal spend wise.
They are however building more “solutions” to try and capture more of the transaction fees, but most people’s disdain for the payment rails would be better redirected at the banks in this case.