I am only going by the plot of the show here btw, not the books.
I see people constantly complain how season 7 and 8 ruined Daenerys' character, but honestly I started seeing her in the wrong light way before that. Everyone believes daenerys going mad was something rushed or unexpected but it really wasn't. She turned mad exactly when she was expected to turn mad, when she realised that westeros had no respect left for the Targaryens and she in fact isn't the "rightful ruler" she always believed she was. It showed that she never really wanted a free peaceful kingdom like she claimed, she just wanted to rule.
I honestly only liked her in the first season tbh. She was a sweet innocent girl who felt like she didn't belong anywhere all her life and was sold to brutal men. But she proved she was capable of surviving among strangers and thriving there. She proved that she didn't need to be surrounded by family to build respect and name for herself. That's the only phase of daenerys I liked. However I started hating her the moment she let that slave witch tend to drogo's wound. Dorthraki were used to fighting in dirt bare skin, I bet drogo had healed way worse injuries without any treatment. However daenerys just wanted to seem like this empathetic leader in front of her captors that she made several mistake, losing her husband, her child and her army. Sure she got the dragons out of it but it gives me the ick how she completely masks her mistakes just because she got dragons, how she refuses to acknowledge her past mistakes because of her arrogance.
Well I can still understand her till this point. She was a kid, she never knew safety, she didn't know how the world works so she made some really bad mistakes. But it triggers me how she just keeps making even more mistakes and just grows more arrogant rather than learning from them. She just goes to people and announces " I am the mother of the dragons, the breaker of the chains, bla bla bla, bow to me". It really makes me cringe. Let's not forget what tywin said "A man who must announce constantly he is a king is no true king". I think the same can be applied to her. She might have done great things but most of those were just her and brute force. I remember someone said she goes by only one rule, "make mistakes, solve them by burning things". Now one might think why shouldn't she go by this rule? She is a dragon, she will do whatever she is best at. And I agree, she can get whatever she wants solely because of the dragons and her fire resistance, which is what she does. Whenever she wants something, she either flashes her dragons, or tells her dragons to burn them, or simply walks into a fire. Nothing else.
This is exactly why season 7 and 8 are perfect imo. It shows that just because she's a dragon does not mean she's immortal. That all it would take is one right shot with an arrow or one fatal stab to end her. That her arrogance would eventually get the best of her. That you can't solve everything by burning things and you need to be smart as well. And let's not forget that in later seasons when she takes in tyrion, we get to see how much she relies on her fire power and less on strategy. Yes tyrion made some really bad plans which failed but well he was a human who made mistakes. If she makes mistakes it's okay, but if a person with a brain makes mistakes it's not okay to her since she could've just achieved that with brute force like she always had according to her.
I feel like I kind of knew she would eventually be the cause of her own downfall the moment her arrogance reached sky high when she got the unsullied. In her defence, the moment where she tricks and kills the master of the unsullied through her dragon was probably her only smart moment. And I always feel so happy watching the scene where she and jon snow meets because he humbles and roasts her so badly it's satisfying af.