Originally Posted by
N639DL
You are the DYKWIA, a very selfish one at that. If it can fit under your seat...put it there! Provides overhead space for something else. I wouldn't call someone out on it because I don't know who's item it is and don't know if anyone actually has any free space under the seat in front of them. It's just very self-centered, and not that much of a sacrifice to just put a bag under the seat in front of you.
So, since (according to you) I have to put my small bag under the seat in front of me, I might as well carry on my larger one and put it in the overhead. That provides less space for others than putting my small bag in the overhead. Why do you find such a situation preferable?