One of the reasons humans love parrots is their ability to talk. We love their vocalizations (well, maybe not the screaming they are sometimes prone to), and we enjoy the feeling of communicating with these intelligent, beautiful creatures.
However, you should never buy a bird only because you expect a talking genius. Frankly, you should assume the bird will NOT learn to talk, because a bird should not be traded in or abandoned just because it doesn’t learn human speech.
Parrots are vocal by nature. Talking is just another way of communicating with you. If they can communicate fine without words, why bother? For this reason, teaching talking is really about associating pleasant and positive events with words. Arbitrarily trying to teach your bird words you think are cool is not very easy.