The main blockchains are slow and expensive by design – every transaction is processed by every node. Layer 2 networks process transactions separately and post summaries back, which makes them fast and cheap while inheriting the main chain’s security.
What it achieved
Transaction costs fell by orders of magnitude. Speed rose to something usable for ordinary interactions. Applications that were uneconomic on the main chain became viable.
What it created
Many layer 2 networks, each with its own liquidity, its own applications, and its own bridge to the main chain. Moving value between them requires bridging, which is slow, costs fees, and has been the site of some of the largest thefts in the sector.
A user with assets on one network cannot easily use an application on another. The fragmentation partly recreates the problem that blockchains were meant to solve.
The security question
Layer 2 networks inherit main-chain security for finality but not for everything. Sequencers – the components that order transactions – are frequently centralised, which introduces exactly the trust assumption the architecture was meant to avoid.
Most operators plan to decentralise them eventually. Eventually has been the timeline for years.
What is being tried
Shared infrastructure so networks can interoperate. Standards for bridging. Aggregation layers that present many networks as one to the user.
The realistic picture
Cheap transactions exist and are widely used. The user experience of dealing with multiple networks remains poor. The consolidation that would fix it is happening slowly and against the interests of every network that would be consolidated away.