سُبْحَانَ ٱللَّٰهِ
Holy Qur'an
Al-Qur'an
Kids Qur'an
The sequence makes it clear that the generic term "man" referred to in this and the next verse applies, primarily, to the agnostics who are either unconvinced of the existence of God or are "bent upon denying the truth"; in its wider implication, however, it applies also to those who, while believing in God, are weak in faith and therefore easily swayed by external circumstances, and particularly by whatever happens to themselves.
Lit., "he is [or "becomes"] utterly hopeless" or "despairing" (ya'us), inasmuch as he attributes his past happy state to a merely accidental chain of causes and effects - in short, to what is commonly regarded as "luck" - and not to God's grace. Hence, the term ya'us, in its Qur'anic usage, is indicative of spiritual nihilism.
He does not realise that some kinds of chastening are good for discipline and the training of our spiritual faculties.