Trouble is, it's a tough number to reach.
In fact, those rates of return will do an investor quite well when the power of compounding is brought to bear. The investor best suited for long-term success is the one with realistic expectations. This is one of the most difficult questions in investing, right up there with discerning an appropriate future growth rate for companies. Unfortunately, it's one of those things that can definitively be determined only in hindsight. And that's where expectations come into the picture.