Why does the saying, "When it rains, it pours" exist. Do you find it to be true?

The past few years of my life have felt like a roller coaster. It seems like when the roller coaster is flying up the tracks everything just keeps getting better, but when I am on that downward spiral it seems as if everything keeps getting worse. I thought about the saying, “When it rains, it pours” and thought to myself, “Hmm, is this saying so popular in society because bad things tend to occur in chunks, and then good things follow in chunks, or is it just our_perception_ of what is going on?” It would be crazy to think that there is some aura about life that causes a “series” of bad or good things to happen in phases.