Hopelessness does not let anyone overcome their worries and deviate believers from Allah’s path. When someone becomes hopeless in the Almighty, he starts denying his powers in a way and distance himself from the truth.
Shaitaan’s favourite weapon is despair, from which he misleads the believers.
As per Ahadith; sadness leads to weakening of the heart, tires one’s courage and hinders the progress. This not only depresses one but also makes Shaitaan happy as his evil scheme to deviate believers gets fulfilled.
When there is nothing that sadness has to offer, why indulge oneself in it. Allah is there to indeed help those who seek his aid and mercy.