I don't understand why Christ doesn't dispatch Satan after Armageddon and be done with it. But if I accept the Bible as the inspired word of God, I can't pick and choose what I like and just discard what doesn't make sense to me. We are even warned in the Bible not to lean on our own understanding. His thoughts are so far beyond our own, we have to rely on His understanding not ours.
I have a feeling, that the millennial reign has to do with the different eras or ages God has designed , e.g. the age of the Innocents, the age of the Law, the age of the Gentiles.
Don't be so surprised about the nature of man. God Almighty, Himself, sat in the Temple of the Jews, (after He had just taken them OUT of slavery), and they politely asked Him to leave. They wanted a mortal King instead. That decision lead them right back into slavery for years.
Man saw the goodness and miracles of Jesus Christ and hung Him on a tree.
And then there will be those that see Christ's return. You would think they would say, OMG It IS Him! It was all true. Let's go to Him. But the opposite is going to happen. Man is going to try to kill Him again. They will
choose to fight Him alongside their leader, the anti-Christ.
If you run into something that you don't understand, pray for discernment and wisdom. God loves to honor that request.
And look to a consensuses of Bible scholars who have done their homework and can make sense of it for you.