See here's the controversial take. I don't agree with you at all. It was literally built up for the entire series and was the only natural conclusion. She was literally saying "I plan to break the wheel" from the start. That is not language a peaceful person uses. Her goals to begin with were those of a conqueror, and what we got was the natural end of that ambition when it crashes into reality.

I think it was done beautifully, and the fact so many people bought into her side of things and felt betrayed is evidence of how well done it was.

But she didn't suddenly lose it.

She wiped out cities full of people before. But it took her doing it in Westeros for people to see that it was because she was insane.

If she didn't like a system that existed, she wanted to burn it to the ground, a person, burn them alive.

Surely putting that person in charge couldn't go wrong.