i've seen people like this too. Not just on cruise ships, but in restaurants on land. It's embarrassing to witness! It just makes me want to be extra nice to the wait staff - as if to say, "It's OK- not all people are rude demanding jack asses!".
Do you think maybe it makes them feel powerful or boosts their low self esteem somehow? I don't know - it's just a really awful thing to be exposed to
What that rude barbarian didn't realize is that the abused waiter might have spit on his two salads- then smiled at him.... <G>. One can only hope-