The evil eye is genuine.

عَنْ رَسُولِ اللَّهِ ﷺ قَالَ الْعَيْنُ حَقٌّ

The man casting evil would be commanded to perform ablution, and then the man affected was washed with it.

كَانَ يُؤْمَرُ الْعَائِنُ فَيَتَوَضَّأُ ثُمَّ يَغْتَسِلُ مِنْهُ الْمَعِينُ