The massive talent pool and ease of recruiting people to come live there from across the world. The access to massive markets. Proximity to a lot of the hot new startups. The desire to have an HQ on both coasts. New Yorkers don't have a right to large tech companies, but the companies would be foolish not to come along.

Amazon always wanted NYC. They overplayed their hand trying to get a break and it blew up in their face.

They probably could have gotten away with most of it if they did this with less fanfare.