Change that endures is more rare than changes that merely oscillate back to the status quo. We chronically flip/flop between extremes because it's human nature to balance every situation so it remains cohesive. We instinctively compensate for one-sided endeavors. The extremes join together in a dance that goes nowhere quickly. All the incessant changing amounts to chronic stagnation.
Freud was amazed when he discovered a death instinct in us. He was focused on the pleasure principle that drives the "Id". Initially, he understood all our wishful fantasies and infantile grandiosity, but not our desire for self destruction, self sabotage and self denigration. The death instinct now makes more sense as compensation for all that exuberance, vitality and buoyant optimism of the pleasure principle. It balances one extreme with another.
Animals give us pictures of the death instinct: a deer in headlights, a mouse spellbound by a snake's eyes or rabbit frozen with terror. Our bodies pump endorphins into our bloodstream when we are about to be mauled. We are feeling no pain when we're getting ripped apart or mutilated. I suspect the same high occurs when we're getting bullied, yelled at or humiliated. Our natural pain killers replace our fight/flight adrenal response.
There's also a connection between guilty pleasures and arranging for punishment. We don't stop with the indulgence, we want the pain too. We think we deserve retribution for our wicked enjoyments. We compensate for feeling good by feeling bad later.
When abuse happens, the experience of extremes is shared with a victim. One enjoys being abusive while the other takes secret satisfaction in getting abused. The predator and prey are bonded in an pattern of chronic oscillation. Both are asking for what they get by being so one-sided.
Persecution is addicting. Underdogs stay down for a long time. Victims repeat the pattern in new environments. Abuse is missed when it's removed. It's suspected that the experience of abuse is an escape from numbness, feeling nothing, going cold. There's a spark, fire and light brought to the darkness of self pity, powerlessness and paranoia -- by the terrifying violence.
All this explains why oscillation is so common. We are hardwired to compensate for other's extremes and our own excesses, even when it's painful or fatal. We are not programmed to change our programming.