If your 401k was in the average European stock market since the 2000, today you would have the same money minus the inflation. The GDP of Europe has increased the last 20 years, yet the stock market did not.
Check the stoxx 50 index to get an average view of the european industry. It has been flat for decades. If you go to particular countries the image is much much worse. For example if you had your money in the Italian stock market since 2000, by now you would have less than half (inflation not accounted).