What is required almost immediately after the engine fails while in the initial climb, let's say between 50 feet and wherever you reduce the pitch attitude to cruise climb, is a surprisingly forceful push forward on the controls to an even more surprisingly nose-low attitude in order to keep the airplane flying. In an airplane with high drag, such as a biplane, you may need to push hard enough to feel light in the seat. Even in a low-drag, streamlined airplane, the push required will be close to that. At altitude a push like this would feel very strange, but would not be that scary or difficult to accomplish. However, following an engine failure on takeoff, you are not at altitude; you are only a few hundred feet above the ground. You would have to overcome every cell in your brain screaming at you to hold the wheel back to stop the descent. Many pilots have given in to that desperate plea, resulting in an almost immediate stall/spin following the engine failure.