That’s what the Preacher did. He said in 2:4-6:
I made great works. I built houses and planted vineyards for myself. I made myself gardens and parks, and planted in them all kinds of fruit trees. I made myself pools from which to water the forest of growing trees.
Again, we try this.
But this experiment failed too.
I hated all my toil in which I toil under the sun, seeing that I must leave it to the man who will come after me, and who knows whether he will be wise or a fool? Yet he will be master of all for which I toiled and used my wisdom under the sun. This also is vanity. (2:18-20)
No matter how hard you work, you still have to leave it behind. Someone else will sit in your chair one day, and they may be an idiot.
Everything in this life is temporary, fleeting, and repetitive. We want happiness, and we try learning, pleasure, and achievement to try to get them. But none of them ultimately give us the happiness we’re looking for. I didn’t even spend any time in the most sobering part of this passage in 2:12-16, which confronts us with our mortality.
If you take a good look at this world, it’s clear that many of our approaches to happiness just don’t work.