Maybe they do not think they are awesome, but are they trying to capture the flag solo because, well.. they are getting fed up with everyone else not even trying to get near the enemy base and just running in circles and fighting in the middle. I know I've had my share of these games and I have often ended up going into the enemy base and carrying the flag alone. Some of these games you cross 3/4 of the field without even one of your teammates coming to help you, eventually being killed by 6 of your enemies that were not busy fighting in the middle.
I'd rather be the lone stupid flag carrier (that does cap!) than the middle-fighting uncooperative HK farmer. That's a whole other kind of stupidity right there. And don't get me started on the 'FFS!!' shouting middle fighting guys, grrrrr.
Downside of being the flag carrier in such a game also is: you will spend the next ten minutes of the game picking your nose on the roof of your base, since everybody is still fighting in the middle and lets the enemy flag carrier have a tea party unbothered at his own base.

But, the essence of this story is: I agree with you that there often are too many idiots in BGs. Mostly I think they are just kids though.
I must also say: I play both on alliance and horde side, and the horde BG population overall seems a little more mature and cooperative. And sometimes, just *sometimes* you get a GREAT group that is cooperative and knows what they are doing. Preferably combined with a few good enemies as well. Those are the best games that make me love PvP and come back into the Bgs :)