Misery is a continuous cycle. Happiness ends in the moment.
When something horrible happens, our hearts and minds expand to find people to pass it on to. Or maybe not pass it on, but to share. When we feel sad, we want to find people who will make us feel better. We seek out comfort. We tell others our sorry tales and seek empathy, a shared experience. We expect our friends to offer their shoulders, our family to offer their laps to rest our heads in, our lovers to offer their arms to envelop us. We publicize our grief, our sorrow, calls of help hoping someone is listening. We turn it into anger and lash out.
It's a cycle that gets passed on from one person to another. Sure, spreading it around reduces its intensity, but in some way or the other, it gets passed on.
When something good happens, we hoard it. We keep those cards close to our chests and guard them intensely. We announce the events to everyone to make people jealous, but the true happiness is something we keep to ourselves. We are fierce of keeping that headiness close to us, because why would we want to dilute that. When moments of joy are so fleeting, we prefer saving them, savouring them. We don't "lash out" in happiness.
Misery is continuous. Happiness is fleeting.
We spread misery. We hoard happiness.