On my flight this week I actually lined up about 5 minutes early. I arrived to the gate about 5 minutes before boarding. I didn't want to go find a seat just to have to return in a few minutes. And, I knew I would be sitting for the next 2 hours so 5 minutes of standing actually sounded good at the time!

You mention this person wanted Row 7 even though it was full. Well, my guess would be that they were either a fearful flyer or superstitious. I would guess many a flights to Vegas have people wanting to sit in lucky row 7.