That is the Fire Nations goal, right? To take over the world, so success would be fulfilling that goal. Besides, we don't aim to make everyone miserable. When we invade a city and take it over, every inhabitant is able to live as they please. Any new leader has to snuff out resistance, however, and most benders become resistance. That's probably why you hate us, isn't it? We took away the benders from your tribe.