What if I need to do this now? Why would I build a distributed postgres snowflake that takes 10 hours to spin up a new replica, requires that I implement my own sharding, instead of using a datastore that is designed to handle all of these things at scale?
There are some pretty decent NoSQL stores now for simpler access patterns. As long as you stay away from nonsense like MongoDB and stick to real databases like Cassandra/ScyllaDB/BigTable/etc you will do fine.
These stores are a fraction as flexible as PostgreSQL/MySQL but do allow scale-out storage and fast primary key lookups and scans. Good for when the size of your data is well in excess of 1TB+ and you don't need anything complex or consistency.
Yes, Visa may need this. Guess what, 1TB+ of transaction data paying 30 center + 2% PER LINE - you'll be able to afford to do something reliable and scalable.
Folks don't realize, noSQL is not actually that scalable except in very narrow ways. And you can spin up pretty good scale SQL stuff with things look AWS RDS, including backups, replicas, snapshots to go back in time etc (noSQL doesn't support a lot of this).