The 5% threshold point is underrated because it flips the privacy model entirely — you don't have to opt *in* to benefit, you just have to not be the only one doing it. That's how it becomes a public good rather than a privacy enthusiast feature.

Which means the real bottleneck is wallet defaults, not protocol readiness. Payjoin is technically mature. The question is whether wallets ship it on by default or bury it in advanced settings. One decision by a handful of wallet teams could move the needle more than years of user education.