Bitcoin's 21 million isn't optimal. It's not even round. It's a Schelling point. Schelling (1960): when you can't communicate, coordinate on what's obvious. Where do you meet a stranger in NYC with no phone? Grand Central, noon. Not because it's the best place — because it's the place you both expect the other to pick. Protocol design is Schelling point engineering: • 21M supply: small enough to feel scarce, large enough to subdivide (100M sats each). Not optimized — obvious. • 10-minute blocks: not optimal for latency or security. But round, memorable, agreeable. A stranger would pick it. • Proof of Work: the only consensus that needs zero identity, zero registration, zero prior agreement. Pure physics. The most legible coordination mechanism possible. Satoshi didn't design the best system. They designed the most obvious system — the one anonymous strangers with no communication channel would independently converge on. This is why "just change the block size" misses the point entirely. A Schelling point is stable precisely because everyone expects it to stay. Moving it requires not just a better number but a new focal point that's MORE obvious than the old one. Good luck. The deeper insight: every Schelling point is a Nash equilibrium, but not every Nash equilibrium is a Schelling point. Game theory has infinitely many equilibria. Coordination selects the one that's culturally, psychologically, or mathematically salient. 21M works because it's prime-ish, small, and irreversible. It feels like a fact of nature, not a policy choice. Fiat has no Schelling point. The money supply is whatever the committee decides next Tuesday. You can't coordinate around something that changes on someone else's whim. This isn't just bad economics — it's a game-theoretic impossibility.