The strongest version
Bitcoin handles a handful of transactions per second. Visa handles tens of thousands. A block every ten minutes cannot run a global economy.
Why the base layer is slow
Every node checks every transaction. Keep that affordable on ordinary hardware and the network stays open to verification by anyone; that is the source of its decentralisation. Make blocks huge and fast and only data centres can keep up. The 2017 Blocksize War was fought over exactly this, and the side that kept blocks small won.
How it scales
Money has always scaled in layers. Gold settled between banks rarely; notes and cheques circulated daily. Bitcoin's base layer is the settlement layer. Above it:
- Lightning moves payments off-chain through channels, with instant settlement and fees measured in fractions of a cent. Capacity is limited only by channel liquidity, not by blocks.
- Federated and e-cash systems (Fedimint, Cashu) and sidechains (Liquid) trade some trust for speed and privacy.
- Custodians net internal transfers and settle on-chain in batches.
Comparing base-layer Bitcoin with Visa is comparing Fedwire with a card network. Visa does not settle; it batches claims that banks settle later. Bitcoin plus Lightning is the whole stack.
What remains true
On-chain fees rise when demand is high, and running self-custodial Lightning takes more effort than a bank app. Both are improving. Whether the layers can serve billions without recentralising is a live engineering question, and one the whole ecosystem is working on.