What about the scene where she burned Sam's brother and father to death for not bending the knee? Or the scene where she crucified all of the masters in Meereen (most of them may have had it coming after doing the same to children, but still)? Or the scene where she burns all of the khals alive? You could argue that last one was self defense, but she wasn't exactly distressed by it. As a matter of fact, she seemed to even enjoy it. Either way,
there are several times in the past where her first impulse was to be pretty damn cruel and vengeful. It's just that she used to have people like Varys, Jorah, Missandei, Tyrion, and even Jon talk her out of these decisions, but they're all either dead or traitors (in her eyes, at least) now at this point. As she said herself in this episode, she's now letting fear dictate her actions & decisions and she plans to use fear (and force) to take the throne and continue using it to maintain power & control once she obtains it. Ergo, she plans to become a dictator.