But they didn't cast aside their goals to set themselves as a goddess to be worshipped in a temple for 3 seasons. Even when the freed slaves elevated Danys above them and worshipped her you could see by the grin on her face that something was not right with her. They also didn't go around westeros demanding that everyone bend the knee to them. The show obviously failed to convey to a lot of viewers that Danys was going mad from the beginning and that her only intentions ever were to be worshipped if she is a good ruler or not is irrelevant to her. Once she realized that only the unsullied and dothraki were the only ones that were going to worship her then her final descent into madness was obvious. The books so far make all of this very clear. She was wasting time by not focusing on her goal by playing slave queen for 4 seasons. If she only wanted to free slaves then there was no reason to stay after she freed them at the end of season 3. She stayed to be worshipped. The situation with the white walkers wouldn't have been as bad if she arrived there two seasons earlier. Yes the slavers came back but she only destroyed one ship of them before they quickly surrendered. They will be back now that she is gone. She is a highly questionable character in the got world.