Referring back to our "Kung Fu Panda" example, normally when you hear the saying that a disciple is not above his teacher, you think in terms of knowledge and skill. The Kung Fu pupil cannot become better than his Kung Fu master because his training can only rise to the level of his teacher's skills. That's true with anything. A math tutor who only learned high school calculus can't take his student up to college level calculus; nor can someone who's taken only three years of Spanish prepare someone for fourth year Spanish.
But here Jesus is not talking about his disciples ascending to a level of success. Rather he is talking about descending to new levels of humiliation and rejection. Jesus is called Beelzebul and his followers must expect to bear the same reproach. The disciples can never be above their teacher. If Jesus is abused and rejected, his disciples can expect to receive the same kind of treatment.
Where does this reproach come from? Well, remember that earlier Jesus warned that the persecution would be spearheaded by the religious authorities. They will scourge you in their synagogues, he says, before they bring you before their kings. That's because Jesus' message of forgiveness and grace flies in the face of the classic religious message, which is one of holiness and law-keeping and obedience. If you're out there telling people they can have all their sins wiped away just by having faith, and you're attracting all kinds of unclean, unsavory types and bringing them into the public places of worship, then you will be called a blasphemer who has no regard for the holiness of God. The entire story of the New Testament church is about this conflict.
Maybe nowadays no one would call you a blasphemer, but if you were to get serious about bringing the truly needy into the church, you might get accused of defiling the church's purity, or endangering the children, or bringing in the bad element and offending all the good Christian families and upstanding members. Just as in the days of Jesus and the apostles, the most prominent religious leaders know that attracting winners, not losers, is the key to having a "successful" ministry. Clearly, they are accomplishing more for God than you and your little band of rejects. And they may even want to remind you of what a loser you are. What a failure. How God isn't blessing you but has abandoned you, otherwise you'd be successful like us. You're deluded. You think you're serving God, but you're serving Satan.
And it's an honor to hear it. Welcome to discipleship. You shouldn't expect to be treated any differently, since your Lord was treated the same way. A disciple isn't above his teacher, nor a slave his master. It's enough that a disciple become as his teacher, and a slave his master. If they have called the head of the house "Beelzebul," how much more the members of his household?