Scientists believe that the complete destruction of predators in nature leads to the mass death of victims. Explain why?

Here is the simplest reasoning: if predatory animals do not exist a priori, then the population of their potential prey multiplies unhindered (a small percentage of death under the influence of natural factors and accidents can be ignored). The number of animals per unit of territory occupied by them increases exponentially (very quickly), in addition, weakened and sick individuals remain alive (they are the first to be caught by predators). The livestock is weakened and deprived of food, hence dying.