It depends on what you really mean when you use the words "get what they want." A loud person who is pushy might get what they want in the moment: they might come into a restaurant or shop, they might get what they want, they might push around their friends and get what they want in the moment, but are they actually getting something good for the future? The quiet person who doesn't always get what they want in the moment, maybe they're getting something that's more important for the future. This can be very valuable to look at as to what you mean by getting what you want.
Now when it comes to this type of practice, we don't want to be a loud person, we'd actually prefer to be a quiet person, but we also don't want to let other people just stomp over us. That's another issue in itself. The quiet person does not have to be a type of person who gets taken advantage of by the louder person. The whole practice here is centering around compassion. What is the reason why we have police, armies, courts, lawyers, judges? What's the reason for it? It's out of compassion for society, because by and large there are too many loud people who are creating problems for the quiet people. So the whole essence of developing more compassion is to give the quiet people a bit of strength. We don't have to allow the loud person to get what they want all the time.