Payment processors don't allow just brute forcing all card numbers a.k.a. card enumeration or card testing [1][2] and card schemes penalise merchants and payment processors heavily if they don't take measures against it [3].
1) https://stripe.com/newsroom/news/card-testing-surge
2) https://stripe.com/blog/the-ml-flywheel-how-we-continually-i...
3) https://docs.stripe.com/disputes/monitoring-programs#enumera...