Despair

Why is it that we are always based around despair? If you were to go up to a total stranger and ask what’s been going on in their life, they would automatically think of something sad that has happened recently. Why is it so easy to lose hold of your happiness, just to be plunged deep into despair? Could it be that our despair is causing other to dive into their own pool of depressing darkness? Could it be like a disease, spreading from place to place until it finally develops into a devastating plague? So if despair spreads to others, could the cure possibly be happiness?