"For the world is Hell, and men are on the one hand the tormented souls and on the other the devils in it."
"The life of an individual is a constant struggle, and not merely a metaphorical one against want or boredom, but also an actual struggle against other people. He discovers adversaries everywhere, lives in continual conflict and dies with sword in hand."
― Arthur Schopenhauer
I don't have exact quotes, but in his main book Schopenhauer said that the world is not good, it is just on the edge of total hell. Like a little more and it would be totally unlivable.
And that nature, the sunset etc., is just a visual thing that has nothing to do with happiness.
Whether I agree or not: it depends on the mood and the period of life.
But it's hard to deny what he said.