It is that very insecurity that will also cause a toxic person to be very unhappy when they perceive that someone else is having some sort of success or happiness. Instead of noticing and appreciating the other person’s hard work to attain their success, they’ll feel indignant and resentful. A dead giveaway that a person is experiencing toxic envy is when they minimize other people’s accomplishments or insult others that they perceive to be doing something well.