Considering that Zelle is largely marketed for p2p and not as a general all-purpose payment mechanism, you need to compare it to Venmo or Square. For reference Venmo is on track for ~$400 billion this year.

Draw your attention to YoY upward volume trajectory in my first citation in the comment you replied to. It is still "warming up." TAM is all existing check, ACH, Zelle, and credit card volume. Takes time for folks to get the warm fuzzies and migrate to new systems.

The faster merchants offer instant payments for making payments for free and surcharge credit card rails for payments (to cover the exorbitant cost), the faster volume moves over (imho).

Brazil's Pix (https://whatispix.com/) is what desired target end state looks like imho.

Brazil's Pix payment system faces pressure from Visa and Mastercard - https://news.ycombinator.com/item?id=48052371 - May 2026 (383 comments)