The consequence would be to decrease your chance of survival. It's all about controlling chaos. Evacuation in an orderly controlled fashion increases the chances of survival over a chaotic rush for the door.
You are only interested in yourself, but the training that the crew goes through is to increase the survival of the highest number of passengers. Sure, your mad rush for the door may save yourself and possibly a couple others behind you but the stampede behind you is not as efficient of evacuation as an orderly controlled evacuation.
History has taught that the chance of chaos is increased if passengers get up from their seats before the plane comes to a complete stop. So the crew puts on their best authoritative voice and tries to make you sit there until the odds are optimum.
Your best chance of survival is to do exactly what the crew says to do. Their training is based on lessons learned from previous real life accidents.