Keep in mind that's not all of the millionaires of New York, probably not even a representative sample (New York millionaires usually complain about how "20 [million a year] is just 10 after taxes"). Most of them are probably happy to get the tax cut even if they won't feel it.
Included in those $9 billion in budget cuts, which have to happen in order to give millionaires a tax break), is defunding of services for homeless youth, including the Ali Forney Center. There isn't even room for sarcasm there as the state tells homeless youth to go sleep in the street (where they'll probably be arrested for sleeping in the street) while it sends money for their future (and many other people's) to millionaires. That's simply wrong, but it's the kind of governance rich people are paying for when they donate large sums to political campaigns.
And the governor of New York who's fighting for this budget proposal? He's a Democrat, working with exalted "centrist" Mayor Bloomberg to loot the state treasury for themselves and their benefactors.
Also, it should be noted that this has barely been mentioned on MSNBC, the "liberal" cable news channel. Although it's based in New York, it hasn't found more than a segment with which to discuss the budget deal that was proposed in its anchors' own state. A search of their site shows that the only mention of Cuomo's budget is this segment from Mornin' Joe, where the anchors fawned over how fast the budget was written up, calling the governor "The Gamer," talking about his "maturity, patience, a soft touch" and saying it sets him up to run for the presidency in 2016.
Get a room!
And what about Rachel Maddow, who hammers Republican governors of states she doesn't live in for cutting taxes even microscopically while proposing budget cuts? The same anchor who relentlessly covered DADT last year in an effort to get it repealed? A search of her show's site doesn't turn up anything for "cuomo"; if anyone knows of a clip, link it and I'll put it up. But she was conspicuously missing from that letter from the millionaires even though she has a seven-figure salary and works in New York.
This is why it's even more problematic for liberals and Democrats to call for budget cuts and tax cuts for the wealthy - people let them get away with it because, for some reason, they have the reputation of being communist socialists who cry over all the poor people of the world while giving welfare queens handouts. They could even call for the homeless to give up a few meager services so they could give millionaires a tax break and some people would still think they're trying to impose Marx's dream on Real America.
That's just theatre. There are plenty of decent Democrats out there, but just having a "D" after one's name doesn't make a politician impervious to the structural forces that are pushing for a feudal state in the US.