I one had a student who was convinced that he already knew how to fly because he had 1000 hrs on MS Flight Sim. When I suggested that was actually not very good preparation he was quite offended so on the first lesson I flew us to the practice area and said I am going to fly a steep turn, enter and recover from slow flight and do a power off stall and recovery. After doing that I said you go ahead and do the same sequence since you seem convinced you already know how to do this it should not be hard for you Not surprisingly it did not go very well at all. After I had taken control over for the third time he turned to me genuinely puzzled why the sim experience did not translate to real thing.
I told him the sims are a game and real flying is not a game. We then spent the rest of the first lesson on attitudes and movements and the light went on. He never touched the sim again and turned out to be a good PPL.