Tail emission and dilution: caps vs forever-money

When the main emission curve finishes, a coin ends at one of two places. A cap: total supply freezes (Bitcoin's 21M is the archetype) — dilution hits exactly zero, and so does the subsidy paying miners, leaving transaction fees as the entire security budget. Or a tail: a small constant reward continues forever (Dogecoin's ~10,000 DOGE per block) — the security budget never dies, and neither does dilution.

Between them sits the compromise most new coins pick: decay curves that land on a *small* tail — cap-like scarcity with a drip of permanent security income.

Absolute numbers hide the story; percentages show it. Say a coin ends its schedule with a 500,000-per-year tail:

The tail never changed — the denominator did. That's disinflation: infinite emission, shrinking effect, year after year. It's why Dogecoin's never-ending printer stopped being a punchline: the same fixed tail against a growing supply trends toward irrelevance on its own.

• Cap buys: a fixed total — the anchor for scarcity narratives, the "21M"-style marketing line, zero long-run dilution.
• Cap costs: a security budget decaying toward zero exactly as scarcity peaks — the fees-must-step-up bet, unproven at Bitcoin scale until it happens.
• Tail buys: hashrate income forever — no security-budget cliff, no "who pays after the last halving" question.
• Tail costs: permanent dilution (shrinking in %, never zero) and the loss of the fixed-supply story.

Project pages state cap-vs-tail up front in Tokenomics, and the Supply card visualizes it: capped coins show a progress bar toward max supply; tail coins show where the current era sits, because "progress toward forever" isn't a number anyone needs.