"We really wanted to use a blockchain and it is the main reason why we build the company in the first place so we never questioned that choice".
If the product poster is using has that property, then perhaps is a reasonable choice.
Postgres does not have any ledger balancing primitives.
The same way Lyft would not even consider using Stripe in its first two years, considering how critical credit card data is for them.
I really like the design you have internally! I would love to hear more about it, can we talk?
Stripe's amazing service also comes at a substantial premium. For a high-volume thin-margin company like Lyft where every penny counts, per transaction fees at 2.9%+ are killers. Furthermore, large companies prefer to own the raw card data themselves as the interchange rates for card not present debit cards is different than card not present credit cards. Once you hit a certain amount of scale this .15% difference is substantial.
(edit: I missed that parent comment was about trust in a 3-person startup, but point is still somewhat valid)
Its internal, only our systems have access, each user/customer is auto created an account on signup, we hold the private keys encrypted with the user's password so we can't access the key itself, keeps track of everything with 100% consistency.
1s block mining and raft consensus settings so pretty much instant and low resource utilization...and massively scalable.
Sorry to say but if I am in any type of fintech, I would never ever outsource keeping track of my customer's account balances and source of truth.