Don.. "Are guys like this incredibly competitive, mean-spirited, just plain stupid, or all of the above?"

Yes... and... isn't it odd? WHY do these idiots do these things? I just slow down and start moving over and nudge them out of the way. Either the idiot allows me in or the next one will. If not, apparently they don't understand the law. Their loss if THEY hit ME. And, they won't... >;-)