What does Ecclesiastes 2:9 mean?

I made myself pools of water, to water from it the forest where trees were reared.

I bought male servants and female servants, and had servants born in my house. I also had great possessions of herds and flocks, above all who were before me in Jerusalem;

I also gathered silver and gold for myself, and the treasure of kings and of the provinces. I got myself male and female singers, and the delights of the sons of men—musical instruments, and that of all sorts.

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.