From a finite, human perspective these observations hold as reality. I know I see them. There are exceptions to almost every expectation. This verse however is not a concession. It is reality. And scripture has recorded Solomon's observation for us to ponder.
These are "under the sun" notations. That phrase is shorthand for a limited, naturalistic, human perspective that only takes into account physical observations and not spiritual revelation. As such, these notations reflect life in a fallen world. Sin twists lives and ruins our experiences and expectations. And so even the best of human efforts come up short... fast runners may occassionally lose races, battles are won by unseen fortune, wisdom goes unrewarded, and chance accidents occur.
But "under the sun" is different than "under heaven". And when our periphery extends to eternity, these obervations don't sting as much. God has given us Himself and that relieves the ache of our heartfelt disappointments on this earth. It brings much needed perspective. Faith is a power greater than disillusioning experience. And the gift that God gives of Himself lasts forever!