Why are passengers always in a hurry to board first as well as get off the aeroplane first even when they are sitting on the last seat?

This has been my observation that anytime the announcement is made for boarding, people throng at the gate, rushing to board first. And as soon as the aircraft docks at the gate, they are in a hurry to jump out of it even before the doors are opened caring less if they are in the front or at the back.