3 This is the evil in everything that happens under the sun: The same destiny overtakes all. The hearts of people, moreover, are full of evil and there is madness in their hearts while they live, and afterward they join the dead.

Read Ecclesiastes 9:3 Using Other Translations

This is an evil among all things that are done under the sun, that there is one event unto all: yea, also the heart of the sons of men is full of evil, and madness is in their heart while they live, and after that they go to the dead.
This is an evil in all that is done under the sun, that the same event happens to all. Also, the hearts of the children of man are full of evil, and madness is in their hearts while they live, and after that they go to the dead.
It seems so wrong that everyone under the sun suffers the same fate. Already twisted by evil, people choose their own mad course, for they have no hope. There is nothing ahead but death anyway.