What does Ecclesiastes 2:13 mean?

Whatever my eyes desired, I didn’t keep from them. I didn’t withhold my heart from any joy, for my heart rejoiced because of all my labor, and this was my portion from all my labor.

Then I looked at all the works that my hands had worked, and at the labor that I had labored to do; and behold, all was vanity and a chasing after wind, and there was no profit under the sun.

I turned myself to consider wisdom, madness, and folly: for what can the king’s successor do? Just that which has been done long ago.

The wise man’s eyes are in his head, and the fool walks in darkness—and yet I perceived that one event happens to them all.

Then I said in my heart, “As it happens to the fool, so will it happen even to me; and why was I then more wise?” Then I said in my heart that this also is vanity.

For of the wise man, even as of the fool, there is no memory for ever, since in the days to come all will have been long forgotten. Indeed, the wise man must die just like the fool!