Are We Still Stuck in the Blockchain Trilemma?

The “Blockchain Trilemma” is the idea that a decentralised network can only truly optimise for two out of three core pillars: scalability, security, and decentralisation.

This concept has shaped the industry’s technical evolution since Ethereum popularised the concept.

Years on, despite huge strides in cryptography, consensus mechanisms, and Layer 2 infrastructure, many blockchain companies are still wrestling with the same core trade-offs.

So, where do we stand in 2025? Are we any closer to solving the Trilemma, or are we just kicking the can down the road?

First, a recap: What Is the Blockchain Trilemma?

In essence:

• Scalability refers to how many transactions a network can process quickly and efficiently.

• Security ensures the network is resistant to attacks and manipulation.

• Decentralization protects the system from control by a single entity or small group, limiting potential for single points of failure.

The challenge? Improving one often weakens the others.

For example:

• A highly decentralized, proof-of-work network may struggle with throughput.

• A highly scalable sidechain may be fast, but rely on a small validator set or a central sequencer, reducing decentralization.

• A secure, fast Layer 1 may become too expensive to use for the average user, pricing out broader adoption.

Where Are the Trade-Offs Happening Now?

1. Layer 2s: Scalability, but at What Cost?

Layer 2s (Optimistic Rollups, ZK-rollups, Validiums) have brought huge scalability gains, processing thousands of transactions per second. But they often introduce centralisation risks:

• Many rely on a single sequencer, creating a bottleneck and potential point of failure.

• Bridges between Layer 1 and Layer 2 remain one of the most exploited attack vectors in the industry.

• Governance over L2 upgrades is frequently held by a small multisig, reducing decentralisation.

So while users get cheaper fees and faster confirmations, the trust assumptions increase, a shift in the risk profile that not all users understand.

2. Appchains and Modular Blockchains

The rise of modular architectures (like Celestia and EigenLayer) and appchains (e.g. Cosmos SDK-based networks) allows projects to tailor their own balance between speed and sovereignty.

But again, trade-offs remain:

• Modular stacks often require multiple layers (DA layer, settlement layer, execution layer), which introduces complexity and relies on interdependencies between chains.

• Appchains may prioritise throughput and control but often start with smaller validator sets, raising questions about security and decentralisation.

3. New Consensus Models vs Proven Security

Protocols like Avalanche (Snowman), DAGs (e.g., Fantom), and newer PoS variants have made bold attempts to improve speed and efficiency. But many of these systems:

• Trade off battle-tested security for theoretical or unproven consensus models.

• Rely on light client assumptions that aren't fully adopted across ecosystems.

Meanwhile, Ethereum and Bitcoin remain slow by design, but trusted due to their massive, decentralised validator/miner networks.

Are We Solving the Trilemma, or Just Moving the Goalposts?

Some argue that we’re not solving the trilemma, we’re simply shifting where the compromises live:

• We offload execution to L2s and modular components.

• We abstract away complexity through UX improvements.

• We rely on cryptographic advancements like zk-proofs to reduce trust assumptions.

Others argue we’re evolving toward a solution… but slowly, and only by embracing asynchronous, multi-layered design as the new norm.

In either case, it’s clear that there’s no “perfect” blockchain. Every design decision reflects a bet on which trade-offs users and developers are willing to live with and which ones they aren’t.

What This Means for Blockchain Companies

If you’re building in Web3 right now, the implications of the trilemma go far beyond technical design. They affect hiring, go-to-market, and long-term sustainability.

• Engineering talent must align with your chosen architecture, building on Solana vs. Ethereum vs. Cosmos requires very different skill sets.

• Product teams must understand the technical constraints they’re working within, especially when marketing scalability or decentralisation to users.

• Security teams must stay up to date with evolving risks, especially in multi-chain or bridged environments.

Make the trade-offs intentional, not accidental.

Final Thoughts

We may never fully escape the Blockchain Trilemma, but we’re getting better at managing it.

In 2025, the real challenge is no longer choosing between decentralization, scalability, and security. It’s knowing which one matters most to your users and designing your tech, team, and roadmap accordingly.

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