The best algo traders I've seen are those who have created a lot and a lot of algorithms. Tinkering, trying, failing. These are all things that help you craft your strategies from infancy to possible alpha generating systems.
Most traders is able to do that some days but no traders can do it every day, and like PipMeUp say you have to win almost every day just to break even.
The money doesn't come into being out of thin air. The money you make from your trade is lost by someone else at the other end of your trade. Because you don't just buy shares from the market. You buy them from some individual like yourself or from a professional money manager.
And that's...