Opt-in privacy is failing crypto

Privacy has been a recurring narrative in crypto for years. Just weeks after Bitcoin (BTC) launched, Hal Finney pointed out the problem in only his second tweet about it, but the concept didn’t gain wider traction until Monero (XMR) arrived in 2014. Since then, privacy has repeatedly re-emerged as a core promise of decentralised money, especially during moments of regulatory pressure or heightened concerns around financial surveillance. 

Analysts are positive that crypto’s future will continue to be defined by the privacy narrative. Investor Balaji Srinivasan argued privacy will define the industry’s following eight years; meanwhile, a16z crypto said privacy will be the industry’s most important “moat” in 2026. Indeed, privacy coins have rallied at the end of 2025 and continue to fluctuate into the start of the new year. At their peak, the sector reached a combined market capitalisation surpassing $40 billion, before falling back to roughly $17 billion. 

Zcash (ZEC) was a key driver of that resurgence, rising by more than 1,300% from late September 2025 to its all-time high and remaining up over 600% at current prices, briefly overtaking Monero by total market volume. Yet despite renewed interest and price momentum, actual privacy usage remains strikingly low. Zcash’s shielded pool continues to hold just above 30% of the circulating supply, while roughly two-thirds of transactions remain fully visible on-chain.

This disconnect exposes a deeper issue. If interest in privacy is rising, why are users not migrating into the very privacy layers designed for that purpose? The answer could just be structural: opt-in privacy is failing crypto.

Opt-in privacy was a design compromise 

In 2013, the pseudonym Nicolas van Saberhagen published the CryptoNote v2 paper, which explicitly framed transaction privacy not as a “nice to have,” but as a core requirement of electronic cash. This paper argued that Bitcoin’s transparency made it pseudo-anonymous at best, and outlined two properties a truly private payment system should satisfy: untraceability and unlinkability.  Andrey Sabelnikov, now co-founder of Zano, worked alongside Nicolas to bring this vision to life, implementing the protocol he had designed. From the start, CryptoNote made privacy the default, baked into every transaction rather than offered as an afterthought.

But as the industry evolved, many projects lost sight of this principle. Rather than pushing the boundaries of privacy-preserving technology, they took the path of least resistance, prioritizing compatibility, performance, and mainstream appeal over user protection. Privacy-preserving cryptography was still expensive and unfamiliar, so newer designs retreated to opt-in models.

This compromise had serious consequences. Privacy became a feature to be toggled on rather than a baseline guarantee. Users who chose the private option effectively marked themselves as having something to hide, while the default transparent experience left the majority exposed. This trade-off may have seemed pragmatic at the time, but it fundamentally betrayed the original vision that CryptoNote had established: that true electronic cash must protect user privacy by design and wasn’t something to bolt on later; it had to be designed into the core transaction model itself.

The biggest network carrying the original default-privacy philosophy is Monero. Launched in 2014, it adopted the CryptoNote protocol, preserving the principles that Nicolas and Andrey had already established. Instead of asking users to choose between public and private modes, the design assumes that financial transactions should be private by default, and that privacy improves when everyone shares the same protections.

Through this philosophy, privacy does not just become a feature, but a network effect. A privacy system is only as strong as the crowd it can hide in. When privacy is optional, the network fractures into transparent and private activity. The private pool becomes smaller, the anonymity set shrinks, and the privacy model weakens in practice, regardless of how sophisticated the cryptography may be.

The Zcash paradox 

Zcash illustrates the central contradiction facing much of today’s privacy ecosystem. On paper, it offers some of the most advanced privacy technology in crypto, including zero-knowledge proofs that can fully shield transaction details. In practice, however, the majority of network activity remains transparent.

Despite renewed market interest and strong price performance, Zcash’s shielded pool continues to hold just above 30% of the circulating supply, while roughly two-thirds of transactions remain fully visible on-chain. The technology exists. The privacy guarantees are real. Yet most users do not use them.

This gap is not a failure of cryptography, nor a lack of demand for privacy. It is the predictable outcome of opt-in design. When privacy is presented as a separate mode, something users must consciously enable, it introduces friction, uncertainty, and behavioural drop-off. Many users default to transparent transactions simply because they are easier, faster, or more familiar. Others may be unaware of the distinction altogether.

The consequence is a fragmented network. Public and private transactions coexist, but they do not reinforce one another. Instead, the private pool remains small, limiting the size of the anonymity set and weakening privacy guarantees for those who do opt in. Ironically, using privacy in an opt-in system can make a user more conspicuous rather than less.

Privacy can only work when it is the default

Privacy is not a behaviour users reliably opt into. It functions as a collective property. The more participants who share the same privacy guarantees, the stronger those guarantees become. When privacy is optional, networks fracture into public and private activity, shrinking anonymity sets and weakening protection for those who do opt in. In practice, optional privacy often makes users more conspicuous, not less.

The repeated cycles of privacy coin interest show that demand is not the problem; design is. Systems that rely on users to actively choose privacy struggle to translate narrative momentum into real adoption. If privacy is to become crypto’s defining moat, it must be treated as foundational infrastructure, not a feature toggle. Financial privacy works best when it is automatic, universal, and secure by default.