Know any "difficult" people?
They may be relatives, business contacts, the disembodied voice on the phone who can't help you at all–they are everywhere!
They push you to the point of losing your composure, perhaps choosing expletives rather than your normal discourse, raise your pulse, blood pressure. They threaten your serenity, and after so much personal work no less.
How can they possibly be a gift to you?
They challenge your beliefs about yourself and your personal metaphysical journey. If you think you've evolved, grown, learned something about life and meaning….they are there to there to remind you that you are not there yet.
That's actually something good. Its a gift of self-awareness and we have no choice but to recognize that our journey is far from complete.