Also, let us not over emphasize only on being smart alone, because opportunity, luck and hard work also have a part to play in your being smart. One thing I have come to understand in life is that we cannot all have equal opportunity which makes smart people sometimes to still end up being successful on different levels.
Luck and the opportunities it offers are what we should never forget of, the point which I specifically highlight in the OP. Sometimes, in fact, oftentimes, luck is what radically changes our life. Truth to be told, it is exactly because of luck that we as individual persons came into this world having been chosen by it from around a billion of other "candidates", so, in a sense, we were all born under a lucky star via our very existence. And if our life started with luck, we shouldn't discard it during our lifetime either. Discarding luck would be as stupid as relying just on it alone, but in the end (as well as in the beginning, for that matter) it all comes down to luck.