Bitcoin Layer-2: Are They Real or Not?

Many Bitcoin layer-2 scaling solutions are actually sidechains, not true L2s. True L2s should inherit the security of the native chain. Sidechains have their own security model and don't automatically support the parent chain's native asset. They rely on pegged tokens and have a higher risk of security breaches. While some argue that the distinction between L2s and sidechains doesn't matter to end-users, others believe the security implications are significant. Lightning Network is an exception, being a genuine Bitcoin L2 with offchain transaction channels secured by the Bitcoin network. ZK-rollups could potentially be implemented in the future with the help of OP_CAT and ZK technology. The surge in demand for scaling due to Ordinals and Runes has attracted venture capital investment in Bitcoin L2 projects. However, only a small fraction of the total investment in Bitcoin L2s has been publicly disclosed, suggesting the actual amount could be significantly higher.