If previously 3 merchants had visa / Mastercard out of 10 who only accepted cash or cheques, then with UPI all 10 now accept UPI but 7 or 8 accept a universal POS which allows more type of payments. If previously 10% payments were via cards that costed them 2%, then now if sales are 2-3x because of UPI and online payments, letting go of that 2% for even 20% share of cards is fine because they captured a larger market with more sales. Not so long ago, India was a cash dominant economy so UPI actually opened that up. UPI actually helped Visa and Mastercard. Credit card spending has gone up a lot because of digitalization.

If in EU a local payment system captures the cash market, then the habit of using digital payments will actually also help Visa and Mastercard make more sale.

I currently don't have a credit card, but when I do, I find paying by a Visa/MasterCard much more preferable than UPI, simply because it's easier by tapping.