Why do copy trading returns differ from the leader?
You copy position changes, not the leader's historical fills. Your entry time, account size, fees and order constraints differ. Full-book copying enters existing positions at current prices; forward-only copying starts from later changes. Neither mode promises the leader's return.
Same direction, different entry
If a leader bought BTC at $60,000 and you start copying when it trades at $65,000, a matching position does not give you their $60,000 entry. If BTC then falls to $62,000, the leader can still show a gain while your new position shows a loss.
Detection time, market movement, slippage and partial fills can also change a follower's entry or exit. A copied order is a separate order in your account.
Your account cannot always hold the same book
Positions are scaled to your balance and risk setting. Small allocations can put an order below the exchange minimum; quantity precision, available margin and leverage limits can change or prevent a fill. Your book can therefore differ from the leader's even when both accounts follow the same direction.
Compare your own net return over the time you actually copied. A leader's annualised ROI or all-time PnL uses a different history and is not a forecast for your allocation. Trading and platform fees also affect your result.
Sources and detail
Copy trading can lose money. Past performance does not predict your results. This is product information, not investment advice.