Yes, it does mean that.
But only relative to the average growth of the market. If the marked is up by 5% a given year, you can buy an index fund (or just a random variation of stocks) and expect close to 5% return.
For the people who keep trading throughout the year, about half will get returns below 5% and half will get returns above 5%.
So if you are not better than the average (by value, not by the number of traders), you should stay away from manual trading.
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