"Many people" is the world. And the world is fallen. If you don't belong to the kingdom of God then you belong to the kingdom of Hell. Because Catholics in state of grace belong to the Kingdom of God, then the world hates them, mock them, and condemn them. Today, the disdain comes from a high level of ignorance and misunderstanding of the Faith combined with a serious anti- Catholic propaganda that pollutes the minds of many worldly people.
“Who is the liar? Whoever denies that Jesus is the Christ. Whoever denies the Father and the Son, this is the antichrist.” (1 John 2:22)
"If the world hate you, know ye, that it hath hated me before you. If you had been of the world, the world would love its own: but because you are not of the world, but I have chosen you out of the world, therefore the world hateth you." (John 15:18-19)