While hard work does have its dividends this does not account for the billions of hard working people in this world who live in poverty. It is easy to fall into the trap of works righteousness. We deserve what we work for therefore God rewards us for how hard we work. This can seriously discount the notion of grace. It is easy to fall into the trap of working for things justifying our obsession of materialism with the belief that this is a sign of God's approval.
Materialism leads to emptiness.
How often have we longed for something only to find that after a day or two after we've played with it, the thrill is gone. And I saw that all labor and all achievement spring from man's envy of his neighbor. This too is meaningless, a chasing after the wind. It is exhausting. It leads to backbreaking debt.