Layer 2 rollups

What a rollup is

An Ethereum layer 2, or rollup, is a separate blockchain that runs on top of Ethereum itself. It executes transactions away from the main chain, then posts compressed records back to Ethereum’s base layer, so that users get much lower fees while still inheriting the security of the underlying network. This design, the rollup-centric roadmap, has been Ethereum’s official scaling strategy for years, and it has worked well enough that the Ethereum layer 2 ecosystem now processes the majority of transaction volume in the network. That success is also the source of the argument now running through the community.

The fee-siphoning argument

The criticism is about where the value ends up. Ethereum’s layer 2 networks handle the bulk of activity, yet they return only a small fraction of the value they generate to the base layer they depend on for security. In effect the main chain provides the settlement guarantees and the trust, while the rollups capture most of the fees, a dynamic critics describe as fee-siphoning. If the L1 secures everything but is paid for very little of it, the token and the validators that underwrite the whole system may be underfunded relative to the economic activity they enable. That worry is the reason the Glamsterdam upgrade refocuses attention on L1 throughput, aiming to make the base layer itself more capable rather than treating it purely as a settlement backstop for the rollups above it. The base layer, in this reading, risks becoming a kind of unpaid guarantor.

The competing chains

The field is not uniform. Base, run within the Coinbase orbit, has grown quickly on the back of an established consumer brand. Arbitrum and Optimism are the two long-standing general-purpose rollups, each with deep liquidity and large developer communities. Alongside them a newer category has appeared: application-specific chains built by a single company for its own product. Robinhood Chain is the notable example, and it brought roughly $500m of volume into the Uniswap fee-switch debate, a sign of how much activity a single well-distributed app can now route through its own Ethereum layer 2 rather than a shared one. Each of these chains competes on fees, speed and the applications that choose to build on it, and together they handle most of the everyday transactions users now make.

The fragmentation problem

That fragmentation raises its own questions. When every large application can spin up a bespoke chain, liquidity and users spread across many venues, and the value that might have accrued to shared infrastructure, or to Ethereum itself, is dispersed further still. It sharpens the fee-siphoning debate rather than settling it, because each new app-chain is another layer capturing fees on top of a base layer that secures the lot. The more the ecosystem splinters, the harder it becomes to answer the simple question of who ultimately funds the security that all of them rely on.

What to watch

The underlying tension is genuine and not easily resolved. The rollup-centric roadmap delivered cheap transactions and mass adoption, which is what it set out to do. The unresolved part is how the base layer is rewarded for the security it provides once almost all the activity, and almost all the fees, sit one level up. Glamsterdam’s turn toward L1 throughput is one answer, an attempt to give the base layer a larger direct role again.

For readers following the sector, the Ethereum layer 2 story is the clearest live example of a blockchain community arguing over how to share the value its own success has created. Watch whether Glamsterdam meaningfully lifts L1 throughput, whether application-specific chains keep proliferating, and how the Uniswap fee-switch question resolves, since it bears directly on who is paid for all this volume. Our crypto explainers hub follows the debate across the wider crypto market.