I've had this happen to me too. Perhaps the firework/parade example would've been better to use than an airplane.
I remember one time my sister and I were at
Disneyland and we wanted to see the night time parade. So we camped out a good hour or so beforehand and grabbed a spot right on the curb on Main Street. I brought a blanket for us to sit on and we waited. At the VERY last second, a family with three kids squeezes past the crowd behind us and tries to shove their kids in front of us. We stopped them from doing so and we had to take the blanket off the ground because the parents tried to pull the blanket out from under us so their kids could sit on it too. Was I rude to block three kids' view of the parade? Sure. But we made the effort to grab a spot early and that was what we wanted to spend our park time doing.
That's why I don't think the OP or anyone else who has done this is in the wrong. I can't stand the entitlement of people, especially if they're the ones coming in at the last minute.