As pretty much any professional trader or quant knows, there are degrees of efficiency. Ex-US markets are significantly less efficient than the US. Some US securities are less efficient than others. Certain instruments and exchanges are less efficient than others.
Markets become more efficient as a result of entities who make them so. It is possible to make a very good living by being one of these entities.
Markets become more efficient as a result of entities who make them so. It is possible to make a very good living by being one of these entities.