Monetary Policy and Stablecoins

Why It Matters

A payment network whose unit doubles or halves in a quarter isn’t money — it’s a position. Rigobon’s thread in the casebook applies monetary economics to crypto and lands on an uncomfortable diagnosis: most cryptocurrencies fail as currencies on both pillars that hold a currency’s value up.

Those pillars: collateral — quality, liquid assets standing behind the unit — and trust — independent management credibly aiming at price stability. Crypto struggles on both: collateral is illiquid or absent, and fixed-supply protocols can’t stabilize by construction — when excitement rises, price rises; when fear rises, it falls. There is no mechanism leaning against the wind. That diagnosis is the entire reason stablecoins exist.

How It Works

Beginner

Why is a dollar worth a dollar tomorrow? Because an institution with deep reserves actively manages its supply to keep it stable — printing less when it weakens, soaking it up when it overheats. Bitcoin deliberately has no such manager and a fixed schedule, so its price floats on pure sentiment. A stablecoin is an attempt to bolt the management back on: hold reserves, peg the price, expand and contract supply as demand moves.

Intermediate

Two further points anchor the casebook’s framing. First, stability must be measured against a consumption basket — what people actually buy — not against the dollar, which itself drifts. A coin perfectly pegged to a wobbling reference is still wobbling. Second, the upside case is concrete: financial inclusion and remittances — roughly 2 billion underbanked people, with fees of 15–25% on a $100 transfer — plus a hedge against abusive central banks. And a well-designed currency shouldn’t need speculative capital gains to drive adoption; if holders are in it for the appreciation, it’s an asset, not money.

Builder

The design space sorted itself into three families: fiat-collateralized (USDC, USDT — off-chain reserves, issuer trust, redemption risk), crypto-collateralized (DAI — on-chain over-collateralization, liquidation machinery), and algorithmic (supply rules without full collateral). The third family supplied the cautionary tale: Terra/UST’s 2022 collapse (~$40B) was Rigobon’s lecture rendered in real time — no collateral floor, trust evaporating, a death spiral the protocol was structurally unable to stop. Regulation has since pulled fiat-backed issuers toward audited, T-bill-heavy reserves — converging, ironically, on exactly the “quality, liquid collateral + trusted management” the casebook prescribed.

Examples

Bitcoin — Fixed supply, no stabilizer: sound-money experiment, volatile unit of account.
USDC / USDT — Fiat-reserve stablecoins; the dominant remittance and trading rails.
DAI — Crypto-collateralized, governed on-chain.
Terra/UST — The algorithmic failure case proving the collateral+trust thesis.

Tradeoffs

Strengths (of engineered stability)

Usable unit of account — pricing, payroll, and contracts need a stable measuring stick.
Cheap global transfer — the remittance case from the casebook is stablecoins’ clearest realized win.
Inflation refuge — a dollar proxy is a lifeline under abusive monetary regimes.

Limitations

Trust reintroduced — fiat-backed coins resurrect the trusted issuer crypto meant to remove; the collateral is only as good as the audit.
Peg ≠ stability — dollar-pegged coins import the dollar’s drift; the consumption-basket standard remains unmet.
Run risk — under-collateralized or algorithmic designs are structurally exposed to death spirals.
Regulatory dependency — reserve quality and redemption rights are now a policy variable, not a protocol one.

Double-Spend Problem — The e-cash → Bitcoin lineage this thread contrasts with
Mining and Mining Economics — Where issuance meets real-world cost

Sources & Last Updated

MIT BLC Module 2 (primary source; Rigobon, Unit 1 thread)
Vault note: Monetary Policy and Stablecoins (M2 cluster; bridges to the planned Economics cluster)

Freshness note: the stablecoin taxonomy and Terra collapse post-date the casebook and are flagged inline.

Last updated: June 10, 2026