Ecclesiastes 2:21

2:21 For a man may do his work with wisdom, knowledge, and skill;

however, he must hand over the fruit of his labor as an inheritance

to someone else who did not work for it.

This also is futile, and an awful injustice!

Ecclesiastes 11:8

11:8 So, if a man lives many years, let him rejoice in them all,

but let him remember that the days of darkness will be many – all that is about to come is obscure.