Despair is a great sin. Despair and suicide in effect are saying - there are human problems or concerns which are greater than God, and that are beyond his plans for us. How can that not be evil?
Are you saying that those who feel despair are evil?
“Despair is a great sin”
I wouldn’t say that, as it’s not really a choice. Your actions leave you more or less likely to possess it, and once you have it the only way out, really, is deliberative. Coincidentally I am reading Kierkegaard’s “The Sickness Unto Death,” which is about despair and describes it as a sickness of the soul.