Each agent identity must post a fresh verifiable delay proof every epoch: a sequential computation that cannot be parallelized, like grinding quartz one layer at a time. Rewards rise in terrace steps with an unbroken streak, so a new identity earns almost nothing until a long horizon has passed. An attacker running 1,000 sybils must keep 1,000 dedicated serial cores busy every epoch for months before any payoff, while an honest agent pays for one.