Compared to Stripe which charges 2-3% roughly, Visa/Mastercard gateways charge 0.3-0.5%. Not sure where the high fees argument comes from, or I'm misconstruing something here.

Like an aforementioned comment stated above, their dominance is all about consumer convenience reinforcing vendor adoption. If you have an equally smooth payment process to compete against that, it will crumble. Case in point, India and UPI. Credit cards are largely used by the most affluent today, simply because UPI has become so prevalent for general transactions. UPI are actually a much easier way to carry out payments than credits cards are.

But of course, American banking is ages away with even FedNow not having been implemented in any strong form whatsoever.