Unit 3 · Level 2 · Layer 2s
L2 economics
On a busy day, a token swap on Ethereum L1 can cost €10-50 in gas. The same swap on a major rollup often costs a few cents, and Ethereum's March 2024 'blob' upgrade (EIP-4844), a dedicated cheap data lane for rollups, cut L2 fees even further. One honest caveat before you celebrate: most rollups today are run by a single sequencer, a centralization their own teams openly acknowledge and plan to fix.
Free to play. No ads, no token, no account needed to start.
What you get asked
A token swap costs €12.00 on Ethereum L1 and €0.30 on a rollup. How many times cheaper is the rollup?
12 ÷ 0.30 = 40× cheaper. Savings like this are why most everyday Ethereum activity migrated to L2s.
Where do those fee savings actually come from?
No magic: compression plus cost-sharing. One batch posted to L1, thousands of transactions splitting the bill.
Most rollups run a single sequencer today. What can it actually do to you?
A sequencer can censor or reorder, which is real power, but it can't fake balances, and users can force an exit through the L1. Annoyance risk, not theft risk.
Match each piece of L2 economics to its role
Cheap fees, a watchful escape hatch, and one honest asterisk about who's ordering the queue: that's L2 economics in four cards.
Most rollups today rely on a single ___, a centralization their teams openly plan to remove.
Judge L2s the way you'd judge any chain: not just by the fees, but by who can interfere and what your exit looks like if they do. 🐜
The rest of this unit
Rollups: do the work upstairs, settle the bill on Ethereum.