The lead typically cannot read music or carry a tune.  Still, his ego causes him to believe he is much, much better than he is.  He sings too loud, forgets lyrics, and his tonal center resides somewhere south of Tierra del Fuego.  He believes the other parts are always getting in his way.  He will tell you that nobody in their right mind comes to hear, say, a bass, baritone or tenor.  People love the melody.  And who sings the melody?  The lead, of course.  So the rest of you, BACK OFF!