To start with, I have lived in poverty, real poverty, not this fake American poverty, where you have an iphone, enough food to be overweight and a roof over your head but still claim to be "living in poverty".
The term "poor" is relative and few if any game designers at WOTC are truely experiencing poverty, and certainly none that will be accepted for this position are. They are only "poor" in the same fashion as teachers, police, social workers and other professions that do not demand a high wage. They do not deserve to make more money than they do.
People make choices and those choices have consequences. If you choose to be a teacher or choose to be an RPG desinger or you choose not to take a good paying job because it is against your morals or ethics then there are financial consequences associated with those actions and you will be "poorer" than others who do not make such life decisions.
Someone with the creativity and editing skills necessary to be a lead game designer and do it well could do a lot of things that would make a lot more money, they choose not to. That might be the right decision, it might be the wrong decision. They might be happier with it, they might be depressed with it but it is a decision with consequences, both financial and otherwise.