Some have recently argued that any rollups below stage 1, such as Robinhood Chain, do not get any security benefit from being a rollup at all, and are effectively an L1 pretending to be a rollup. I want to explain why this viewpoint is incorrect, and why a chain can legitimately benefit from being a rollup even if the operator intends to fully control the chain. The core difference between a rollup and an alt L1 is that a rollup *proves* its state transitions on Ethereum, so the L2->L1 bridge is secured by proofs, whereas an alt L1 typically connects to Ethereum through a multisig bridge. The argument is that since a stage 0 rollup operator has full control over the rollup, the proofs don't matter, because the operator can just steal all bridged funds anyways. But that argument is wrong because it's conflating the two types of attacks that users worry about: - Hacks -- can a third party, say North Korea, steal my funds on the chain? - Counterparty risks -- can the chain operator itself screw me over? A stage 0 rollup doesn't address counterparty risk -- the operator can indeed steal/freeze your funds -- but it's a huge security improvement against hacks. Whereas you could steal bridged funds by just hacking the bridge multisig, with a rollup you must either hack the proof system, or (in the case of OP rollups) silence the challengers for 7 days. Either way it's much harder. But what if the hacker just hacks the operator? Isn't the operator itself a multisig that controls the chain? Yes, but the key difference here is that whereas a bridge multisig is an *active* multisig that's out there signing every bridge transaction, the operator multisig that can upgrade the chain -- if handled properly -- is an *inactive* multisig that's only invoked when something needs to be fixed. In other words, it's the difference between a hot wallet (bridge multisig) and a cold wallet (security council / operator multisig), and we all know that cold wallets are MUCH more secure than hot wallets. That's why the big bridge hacks have been against multisig bridges, not rollup security councils. What stage 0 rollups don't do is reduce counterparty risk -- you do have to trust the rollup to not screw you. But honestly if you are a reputable company like Robinhood, most users do trust that, which is why Robinhood probably sees no reason to ever get to stage 2 and give up their control. In fact, arguably most users *prefer* that Robinhood keeps control over the chain, so as to protect them from hacks, bugs, and even user errors. Security councils can be a feature, not a bug! Besides security, there are also practical engineering benefits to being a rollup. Thanks to mature rollup stacks such as OP Stack and Arbitrum Nitro, projects can quickly spin up a new rollup, knowing the code they run has been battle-tested on billions of TVL. Running an alt L1 requires using much less mature stacks, with much less tooling support. To sum up: - The stage framework is a way to evaluate the security of rollups from the lens of decentralization, but it's not the only way. Some users honestly value protection from reputable parties more than they worry about being attacked by the parties themselves, so it's reasonable for some rollups to preserve control in order to serve those users. - You can benefit from launching a rollup over launching an L1 even if you don't ever intend to go to stage 1/2 and give up control. Your engineers will thank you for choosing a mature stack with great developer tooling, and your users will thank you for reducing their chances of getting hacked. The beauty of Ethereum is that, because it's a programmable system that is itself maximally trustless, permissionless, and secure, builders can build systems of whatever level of trust, permissions, and security on top. We live in a heterogeneous world where people have different needs, so it's necessary that different types of chains exist, and it's awesome that they can all interop with each other through the one and only credibly neutral, global settlement layer -- Ethereum.