Second-I don't feel the GB are bad people, I think most witnesses including them are misguided by something that has been drilled into their heads since they were little and are actually sincere people.
I understand your point of view I really do. As others have said they are captives of a concept. I certainly can't say for sure whether the current GB know the truth about some of their teachings, but in the 60s and 70s the reality of 607BCE and the destruction of Jerusalem was making VERY clear to then GB. 607BCE is of course critical as it underpins so many of JW's beliefs. When the kingdom begins to rule, Satans expulsion from heaven, the last days beginning, the resurrection of the apostles, the appointment of the F&DS...
They had an opportunity to deal with a difficult problem. That they had been, for decades, preaching and teaching something as true but was actually false. Did they grasp the nettle? No.
That's why I can't believe this is Gods organization. They know what they teach is as fact is false. They may well justify in their hearts by saying evidence might come to light later on, but that's false reasoning as 539BCE comes from the same evidence as 586/7BCE. So as Deut 18:21 says...
And in case you should say in your heart: “How shall we know the word that Jehovah has not spoken?” 22 when the prophet speaks in the name of Jehovah and the word does not occur or come true, that is the word that Jehovah did not speak. With presumptuousness the prophet spoke it. You must not get frightened at him.’