I'll give my version of why I think Harry is not just a twit but an obnoxious, entitled person who should have nothing to do with the institutions of state.
We have a system for the head of state in our country which exists because the head of state, i.e. the king or queen, and some immediate members of his or her family, serve us and represent our nation. Other countries have different systems for their head of state, but our system represents the constitutional evolution of our country, our history and our culture. It's actually a very effective system because it is completely apolitical and the head of state can therefore act as a unifying figure, unlike many other heads of state. There is a lot of added value for our country with this system.
Because it is a historical and hereditary system, to be the head of state and a so-called working royal the "social contract" between the royal family and the people is that they serve us, the people and put the interests of the state and of the people above their own personal interests and their own ego. They only enjoy the status they do because they serve us, not because they are kings and princes. If you don't want or can't do that, then just get out of the way. It's happened before, e.g. Edward VIII.
Harry and Meghan tried to upend that social contract but still expected to have all the status and honours and privileges of being a royal, and a working royal at that. The half-in, half-out thing they envisaged was ridiculous. Harry always thought he was important because of his birth and never seemed to understand that it's not his birth that could make him an important person but what he did with the situation of his birth.
Then he went and publicly attacked his family in the most heinous way possible. No one who publicly attacks their family like that in public could ever be considered trustworthy or expect to be able to continue in the family business. Yet he thought he could! Even if your family are really nasty, you don't wash your dirty laundry in public. Except Harry's family are not really nasty and none of the horrible aspersions they cast on them have any credibility to them.
On top of that, his family also represent an important state institution and Harry cared not a whit as to whether his attacks harmed the institution, the British state or the monarchy. Yet he still wants to retain all the privileges and honours of the institution!
For all those reasons, Harry is an insult to me as a British citizen. He has broken the social contract but still imagines I should consider him my representative and elevate him to a glorious position, and listen to all his pontificatings on various subjects he has no knowledge or understanding of simply because he is a prince of England. And he and Meghan still want to be known as the Duke and Duchess of Sussex while being totally undeserving of those titles. They still try to sneak the HRH in if they can and insisted on their kids being prince and princess, when they were still residing in the US.
(For the record, I don't think they should be stripped of those titles; they will wither away over time.)