Why was there a witchcraft scare in Massachusetts in 1692?

There were several contributing factors behind the Salem witch trials. One major factor was a cabin fever effect; the Salem community was small and insular, and because travel could be dangerous at this time, few people ever left the village. This, combined, with mass hysteria, turned what may have been a simple bout of irritation into an epidemic.
Most of the accused witches were people who were simply unpopular or unwanted in the community. The first three accused were Tituba, a Caribbean slave, Sarah Good, a homeless beggar, and Sarah Osborn, an elderly woman. All three of these women were in some way, shape, or form undesirable to their community. Whether the girls who accused them were genuinely trying to get them killed or were simply playing a game, they likely thought no one would miss the three women. They also likely had no idea how quickly the witch scare would spread.
Accusing one's neighbor of witchcraft became something like a trend. Keep in mind that few people ever left Salem, so if you didn't like someone, you were stuck with them until one of you died. Suddenly, people had a way to get rid of pesky neighbors: accusing them of witchcraft. It also became a way to deflect from charges of witchcraft; if you were accused of being a witch, you could always turn the blame on someone else and say that they made you do the horrible things of which you were being accused. The witch trials became an effective, if horrifying, scapegoat.
https://www.history.com/topics/colonial-america/salem-witch-trials