I'm not sure I understand what you mean by, "80 kts momentum pushing you". The instant the wheels leave the ground, the ground's relative motion becomes irrelevant to the airplane, as far as it's performance is concerned. It's only relevant with respect the the pilot's desire to position the aircraft relative to the runway or a departure course, etc.
Its not about groundspeed. The airplane in moving in direction A. That momentum in turn is in that direction. If it turns instantaneously to that opposite direction B the momentum moving in direction A needs to be overcome and accelerated towards direction B.