The great thing about a witch hunt is that witches, being imaginary, can be hunted forever. This gives the hunters great power, as long as they can "keep us the skeer." See, e.g., PoundMeToo, "I'm just glad we ruined Bret Kavanaugh's life," “You cannot be civil with a political party that wants to destroy what you stand for, what you care about.”
The actual, historical witch hunts were fights between the early Protestant and established Catholic churches. They were directly purging others, or showing that they could protect their people from the Devil better than that other church could, by burning more witches. The "little ice age" crop failures and famines were good excuses to look for witches.
So, in essence, the witch hunts were the religious version of the crack wars. New opportunities open, various syndicates fight over territory. Murders spike. Eventually, the territories settle down and the factions come to agreements over boundaries. The murders drop.