Biscuit is right on. This is an aspect which instructors have to be vary aware of, and be assertive as needed to change an attitude - of decline further training, for poor attitude, which I have done. Often, "successful" [men] decide to learn to fly. As Biscuit correctly observes, they pushed the rules to get where they are, so they think they can push flying too. These people are often very assertive and politely intimidating. A new instructor may not feel themselves at a station in life where they can assert back - but they must. So yes, allow the student to safely scare themselves, and if they don't recognize being scared, tell them they should be scared, I have done this a number of times, often repeating the unsafe technique at altitude, until it results in the inevitable spin entry, then handing it back to them for recovery. Usually, that gets the point across. Among this is to accept and consider the advice of others - particularly the master of the aerodrome! And, sometimes aerodromes are PPR - for a reason which might not be self evident - until you ask. In the mean time, they're private property - even type A people understand trespassing!
I've done a number of type checkouts on advanced complex singles (generally Cessna amphibians) and, anticipating a Type A personality, had a stern talk early on, as to what the training is going to be like. This usually sets the necessary tone. But, I'm content to be assertive to the extent required, I'm empathetic that a new instructor might be less so.
For this accident, the poor pilot attitude is evident, and it was certainly the major underlying cause. But, reinforcing this pilot's overly "can do" attitude, is the fact that he did get the plane safely airborne in less than ideal runway conditions. His mistake was not lowering the nose and accelerating to a safe climb away speed. That error is at the feet of his instructor. Candidates must be taught that pointing a plane up does not always assure a climb, and just getting airborne is the worst time to try for it! I have encountered this during training (and "real life") teaching on the water. We nearly never have a defined water takeoff distance, and teaching short field takeoffs on the water is necessary, along with decision making that it cannot be safely accomplished. Once we have agree that the distance is sufficient, and a takeoff is the right decision, (knowing that we have an obstacle ahead - trees on shore), I teach once airborne, to aim at the half height of the trees as though you plan to take the trees out with the plane. Keep flying at the half height until you just can't stand it any more, and then raise the nose just high enough to assure clearing the trees. This works pretty well. It should never be a needed technique on a declared length runway, performance charts, and appropriate calculations should prevail. But, once you're "away" with a plane, it's a better technique than dragging the plane toward the obstacle, having never achieved a safe climb speed.