What was going to keep them there for 10 years, let alone 25?
What else was it going to cost New York and New York?
You seem to be basing your entire view of it being a good call on the possibility of them just leaving. Admittedly possible given some slightly nonsensical laws in the state but rather unlikely. If they moved it would be because they are now unable to fill all the needed jobs in a given area. Like they're doing right now. And they are not exactly dumping their Seattle HQ. But okay, let's do some admittedly imprecise math.
This site tells me that on Q1 of last year the average New Yorker made $3087/week. My hatred of them earning more in a week than I do in a month aside, that works out to $160,524/year.
And putting that number in
this calculator tells me that people would have to give $49,834 right back to the tax man. Cool, however only $9,683 are going to the state. and those measly $9k (not rounding) multiplied with the 25,000 employee positions gives us...oh, $242,075,000
Divide your $3b in those and you get..a little bit more than 12 years. This is assuming Amazon themselves does not pay a single penny in Tax, and that nobody buys any fuel with it ($0.45/gal in tax) or a pack of cigarrettes ($4.35/pack on the state, $5.85 in NYC proper) or indeed anything (4% tax on NY state, 4.5% within the city). It also assumes that their wages stay the same and that the tax rate will not change.
NY letting HQ2 go was a baaaad call for them, and it will cost the city and state a lot of potential revenue.