Copy trading sounds easy, but is very complex. It really only works if you copy the trader for a long time (like years) as your investment is not synced with theirs. For example, a trader buys XYZ at $1 2 years ago, and is now $2 and you copy. Your trade will in XYZ will be the percentage the $1 was to his investment at the time but you buy at $2 up to the same percentage of your invest. OK, it drops to $1.50 and the trader sells, showing a 50% gain but it is a 25% loss for you. You are not copying in sync so trades have completely different outcomes to his.
PS: I copy all my investments but don't expect to copy their returns for at lest a year. It is very frustrating to see your copyee up 20% when you're down 20% copying him (or her). That's what I'm facing at the moment.