Selfish Airline Passengers

So what has irritated me today? Airline passengers that feel they are sooooooooo important that they MUST USE ALL THE OVERHEADS. I have several times had to check my bags when catching a flight and being one of the later passengers to board. Today I witnessed a complete jerk that simply had to have all of his stuff in the overheads. I managed to get early boarding status for my flight - which I don't normally get primarily due to the shorter flights I take - and was on board early. I also managed to score an exit row seat (again not enough status for First class or Business Class) so I had decent leg room. I stuffed my smallish carryon in the overhead, crumpled my overcoat up and jammed it in on top of my carryon, and then threw my PC under the seat in front of me. I had plenty of leg room to be quite comfortable for a 1 hour or so flight. The guy right behind me piles his fairly large carryon (nearly the limit) into the overhead, then hoists his laptop bag also into the overhead, then tosses his coat in, and pours himself into the exit seat across the aisle from me. Now he had a slightly larger bag than me, but he fully consumed an overhead whereas I left enough room for some other soul to place their bag in should they need to do so. Why is it that so many people have to be so selfish.