I lived in Manhattan for 25 years and left 4 years ago and still go back regularly on business. You are not telling the truth about the decline that is going on.
But if you say you've been there 25 years, that's longer than me so please give specifics (and please don't just regurgitate statistics).
I detest the NYC mayor just as much as you probably do, but that doesn't take away from the fact that New York City is a great city. I like to think that the city thrives in spite of the inept and corrupt leadership. Imagine how much better it could be with true conservative leadership.