Bank 4.0 Review: Why Stablecoins Are Rebuilding Banking From Scratch

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Forget everything you know about your bank for a second.

Now build it again. From scratch. With the tech we have today.

Would you build physical branches?

Would you create paper money?

Would you make someone sign their name with a pen to prove who they are — a first-century artefact that's easy to forge and not even unique?

Would you design a mortgage that needs 17-20 pieces of paper to process?

...No. Obviously not.

That's the question Brett King asks in Bank 4.0. And honestly? It's the most important question nobody in traditional finance is answering.

i read it. i finished it. here's what i think held up — and what didn't.

Your Bank Is Medieval Software

King lays it out clean in the opening chapters.

The bank you use today is a stack of medieval artefacts dressed up in software.

The Medici family in Florence built the basic shape of it. The Knights Templar in the 1100s created the first international banking network — instead of physically moving gold across dangerous territory, they let rulers deposit assets in Templar fortresses and travel with coded letters of credit.

Sound familiar?

That coded letter of credit is your debit card.

Your debit card is a 1850 passbook made of plastic.

Apple Pay is that plastic card, copied again into your phone.

The branch? Hasn't fundamentally changed since Monte dei Paschi opened in Siena 750 years ago.

We've been doing design by analogy this whole time — a term King borrows from engineers. You solve a new problem by looking at how something unrelated solved theirs... and you steal the idea.

Von Braun's V-2 became NASA's Apollo became every rocket since.Carl Benz didn't build a faster horse carriage. He took an engine and built the first car.Steve Jobs carried a block of wood around the office to remind his team a phone could start from nothing.

When the internet arrived, what did banks do?

They took the branch form...

...and retyped it into a browser.

Online banking is a branch, in a browser.

Mobile banking is the same form, but smaller.

Nobody asked: does the form need to exist at all?

The Neobank Problem Nobody Wants to Admit

King dedicates a big chunk of Bank 4.0 to the heroes who were supposed to strip banking down to its raw function.

Revolut. Monzo. N26. His own startup, Moven.

Beautiful apps. Fast sign-ups. Great UX.

But here's the thing King doesn't say loudly enough in the book —

They never touched the rail.

When you tap your Revolut card, Revolut hands the job to Visa or Mastercard.

When you do a bank transfer, it goes through ACH — a network that settles in batches — built in the 1970s.

The neobank is the front end. The back end is the same 50-year-old plumbing everybody else uses.

That's not a new bank. That's a prettier app layered on top of the old bank.

And the numbers prove it:

76% of neobanks still lose moneyAverage neobank earns ~$45 per user per yearAverage traditional bank earns ~$350 per user per year

The ones that survived? They did the oldest thing banks do.

Lending.

Nubank makes money on credit cards and loans.

Revolut turned its first real profit when its loan book grew.

The neobank that lived... became a bank.

King set the bar at "rebuild from zero." His own heroes cleared it... by rebuilding the same thing with better packaging.

The Chapter He Couldn't Write in 2018

King comes closest to the real answer — and then backs away.

He writes about what "inevitably emerges when you have to retrofit money, value stores and payments systems to a real-time world sitting on the IP layer, directly accessible by the user rather than through a gatekeeper."

Read that again with stablecoins in mind.

He was describing stablecoins without being able to name them properly. The book came out in 2018. ICOs were still the "killer app." John McAfee was promising Bitcoin would hit a million dollars.

King knew Bitcoin wasn't the answer in its volatile form — take the volatility out and you land exactly on what his own logic was pointing at.

He just couldn't say it yet. So he called it "a futurist's perspective" and moved on.

Eight years later... stablecoin adoption is loudest where:

Local currency is shaky ✓Banks are slow ✓A phone is the only branch anyone has ✓

Which is the exact same shape as M-Pesa.

The M-Pesa Blueprint

The most important section of Bank 4.0 isn't about neobanks.

It's about Kenya.

In 2005, seven out of ten Kenyans had no bank account.

Today, nearly every adult uses mobile money. Around 40% of the country's GDP moves through M-Pesa's rails.

The legacy banks saw it coming. They lobbied the finance ministry to investigate M-Pesa before it got too big.

They were already too late.

First principles win first in the places the old system never bothered to serve.

This is the real pattern. Not Revolut. Not Monzo.

The genuine rebuild happens where there's no legacy system blocking the path.

Kenya had no incumbent bank structure powerful enough to stop M-Pesa.

Argentina, Nigeria, Turkey, Vietnam — no incumbent currency stable enough to stop stablecoin adoption.

The experiment runs where the friction is highest and the legacy is weakest.

What King Got Right vs. What The Industry Did

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The Real Answer to King's Question

If you build a bank from scratch today, you don't build a bank.

You build a money movement tool. Utility. Infrastructure.

Remove the cards, the signatures, the branches — and you see how they were blocking what you actually wanted: value moving from point A to point B, instantly, cheaply, without a gatekeeper.

The "bank" disappears. Only the function remains.

That's what stablecoins on-chain actually are.

That's what crypto, for all its dead tokens and noise, is genuinely attempting.

King dared banking to picture itself starting today.

Almost nothing around us would survive the question.

And we'd keep it anyway.

Because first principles is a beautiful idea. But actually using it means you look at the thing you've built your entire career around — and admit you might not build it again.

So the idea stays admired.

And unused.

Bank 4.0 is essential reading — not because it got everything right, but because it asked the right question. The answers are still being written on-chain, one protocol at a time.