Egos & Do Gooders

I am reluctant to write this post, but feel so strongly about the subject that I feel I must. I am completely conflicted about volunteering for environmental groups because there are so many egos involved. In my experience I have found that the people I meet who are most inspiring are also handicapped by their monstrous egos. They work tirelessly and passionately for environmental causes, but hurt those around them by lashing out because they want to be the "hero" who saves us all. They stand alone in their fight and forget about the other volunteers standing beside them wanting to lend a helpful hand.
I have had two recent experiences where I have gone out with the best of intentions to help out and have been verbally assaulted in the process. The most recent incident the organizer of the event came out to find all the volunteers standing around waiting for direction. As we were all standing there they said to another volunteer, "Can you just get these people out of here, they are in the way, this can happen." Now this was my first time meeting this organizer, and this was my first impression, I was in their way like a piece of garbage. Now I am a passionate person as well, but really is this way to treat someone who is just there to lend some help? I'll tell you my reaction was not so great, I got my personal belongings and went up to another volunteer to explain I was leaving. I felt awful making this decision because I believed in the event, but I also didn't feel right staying.
Why is it that egos often get in the way of helping out? Is this why the green movement could be destined to fail, because everyone is so self involved that they can't let others help them in their quest? Or is it better said that perhaps these environmental leaders and pioneers just want the glory all to themselves? That their egos get in the way of all the good they are attempting to do and therefore it negates the very thing they believe in.
What do you think? Has this happened to you to?