If the polls are to be believed, Cynthia Nixon is going to be absolutely crushed by Andrew Cuomo in the Democratic primary.
So why should I care about Nixon's futile campaign?
Because of what she's saying, and because of the reaction from the establishment.

"The time is up for corporate Democrats, for politicians who campaign as Democrats but govern as republicans," she said. "It can't just be business as usual anymore. I know that our country can do better. We have to turn the system upside down."
..."We have too many corporate Democrats like Andrew Cuomo," she said. "It's hard for some Democrats to do right when they are getting millions and millions of dollars to do wrong. The election of Donald Trump was a wake-up for progressives all across this country. But even before Trump, the establishment was rigging our economy and our government to benefit those on top."
She also emphasized her platform's priorities, including: marijuana legalization, education reform and universal healthcare.
"If 2016 taught us anything, it's that Democrats can't give voters something to vote against," she said. "We have to give them something to vote for."

That's excellent stuff.
So how do you think the Democratic Party establishment has reacted to her?
They freaked out, and starting smearing her.

“Cynthia Nixon was opposed to having a qualified lesbian become mayor of New York City,” Quinn told the New York Post. “Now she wants to be an unqualified lesbian to be the governor of New York."

That one blew up in their faces. I read that Nixon embraced the smear.
So they changed tactics.

the recent announcement by actor Cynthia Nixon that she would challenge Gov. Andrew Cuomo in the Democratic primary for governor, however earnest her effort may be, is hard to take seriously.
...But in the final analysis, if Nixon merely succeeds in giving Cuomo a second black eye, in addition to the one he already has with the conviction of his former right-hand man, Joe Percoco, what good would that do?

What's the point if you can't be sure of winning, hmm? Better not even try.
But this is the response I like best.

Cynthia Nixon, the actress and activist challenging New York Gov. Andrew Cuomo in the state's 2018 Democratic primary will not commit to winding down her campaign if Cuomo wins the party's nomination in September.
..On Thursday, Nixon demurred when asked if the WFP's potential support, and a place on their ballot line, would encourage her to run as a third party candidate if she failed to oust Cuomo in the Democratic primary.
"I'm not prepared to say," she said in an interview with New York public radio station WXXI.

This is where Democrat loyalists throw a tantrum.

Nixon isn't the only one who would be faced with a tough decision if defeated in the late summer primary. Cuomo is already backed by the Independence Party, which also has its own ballot real estate. He secured their support in late December of 2017.
If either candidate were to extend their campaign through the general election after losing the primary, Democrats would risk splitting their vote and opening a path for the Republican nominee to score a major upset. The effects would likely be felt down the ballot, too, as the party pushes to reclaim a hold on the state Senate majority.

So Nixon's campaign could be a catastrophe for the entire state! Be afraid!
Despite Nixon having "no chance" and should "drop out for the good of the Dems", her campaign has already shed some light on the corruption of the NY Democratic establishment.
Most notably was the way the so-called Independent Democratic Conference suddenly became loyal Dems when Cuomo called.
It was done in such an obvious, in-your-face way that the corruption was hard to miss.

Another political roach that scurried out from under the fridge and into view was Cuomo's relationship with NY labor unions.

Union leaders closely allied with Gov. Cuomo are considering creating their own ballot line to back him as the left-leaning Working Families Party is moving toward nominating Nixon for governor, sources told The Post.
Cuomo ran on the WFP ballot line and 2010 and 2014. But many of the WFP’s activists have soured on him, and see him as an opportunistic progressive.
...But the labor unions are looking at creating their own ballot line to back Cuomo and might even call it the “Real Working Families Party” or “Labor Party” to steal the WFP’s thunder, sources familiar with the discussions said.
...The Cuomo campaign suggested that the WFP is dividing the left, just as it criticized the Independent Democratic Conference in the state Senate of doing.

How familiar does this sound? It's Hillary voters yelling "Bernie bros" all over again.
And just like Hillarybots, they never criticize Democrats that vote Republican. They only denounce progressive Democrats that don't fall into line behind the establishment.
Nixon probably won't win, but she can give them Hell.