Why work, make, build, seek, develop, create ....?

So, if there is no rhyme or reason in things, what is the point in doing anything?

What does man gain from all his labour at which he toils under the sun? Ecclesiastes 1:3

Yet when I surveyed all that my hands had done and what I had toiled to achieve, everything was meaningless, a chasing after the wind; nothing was gained under the sun. Ecclesiastes 2:11

What does a man get for all the toil and anxious striving with which he labours under the sun? Ecclesiastes 2:22

What does the worker gain from his toil? Ecclesiastes 3:9

This too is a grievous evil: As a man comes, so he departs, and what does he gain, since he toils for the wind? Ecclesiastes 5:16

Nothing seems to do any obvious good:

Then I thought in my heart, "The fate of the fool will overtake me also. What then do I gain by being wise?" I said in my heart, "This too is meaningless." 16 For the wise man, like the fool, will not be long remembered; in days to come both will be forgotten. Like the fool, the wise man too must die! 17 So I hated life, because the work that is done under the sun was grievous to me. All of it is meaningless, a chasing after the wind. Ecclesiastes 2:15-17

22 What does a man get for all the toil and anxious striving with which he labours under the sun? 23 All his days his work is pain and grief; even at night his mind does not rest. This too is meaningless. Ecclesiastes 2:22-23

As goods increase, so do those who consume them. And what benefit are they to the owner except to feast his eyes on them? Ecclesiastes 5:11

It will only make you an object of envy:

And I saw that all labour and all achievement spring from man's envy of his neighbour. This too is meaningless, a chasing after the wind. Ecclesiastes 4:4

You can’t take anything with you:

18 I hated all the things I had toiled for under the sun, because I must leave them to the one who comes after me. Ecclesiastes 2:18

There was a man all alone; he had neither son nor brother. There was no end to his toil, yet his eyes were not content with his wealth. "For whom am I toiling," he asked, "and why am I depriving myself of enjoyment?" This too is meaningless--a miserable business! Ecclesiastes 4:8

Naked a man comes from his mother's womb, and as he comes, so he departs. He takes nothing from his labour that he can carry in his hand. 16 This too is a grievous evil: As a man comes, so he departs, and what does he gain, since he toils for the wind? 17 All his days he eats in darkness, with great frustration, affliction and anger. Ecclesiastes 5:15-17

What you do leave behind will probably be mismanaged after you have gone:

19 And who knows whether he will be a wise man or a fool? Yet he will have control over all the work into which I have poured my effort and skill under the sun. This too is meaningless. 20 So my heart began to despair over all my toilsome labour under the sun. 21 For a man may do his work with wisdom, knowledge and skill, and then he must leave all he owns to someone who has not worked for it. This too is meaningless and a great misfortune. Ecclesiastes 2:18-21

So must not all work be judged as ‘meaningless, a chasing after the wind’ Ecclesiastes 1:14 ?

It is to this pessimistic conclusion says the preacher that optimistic expectations of finding the divine purpose of everything will ultimately lead you:

Then I applied myself to the understanding of wisdom, and also of madness and folly, but I learned that this, too, is a chasing after the wind. 18 For with much wisdom comes much sorrow; the more knowledge, the more grief. Ecclesiastes 1:17-18