Here's the thing. It's true that the W isn't as popular, or nearly as popular, as the NBA. The WNBA players aren't claiming that it is. Nor are they claiming that they should be paid anything close to LeBron or other NBA players. But what they are contending is that 1) their game is popular, that it gets good attendance and rising TV viewership, 2) that given the popularity and resiliency of overseas women's basketball pro leagues, it suggests that there is the potential for a strong pro league in America, and 3) that the NBA is starving the WNBA of investment, ignoring its potential, falsely claiming that the revenues aren't what they are in order to keep salaries low, and that with good marketing and strong investment, the WNBA can make far more money- for the league and for the players.
And let's keep in mind that this movement by the WNBA players is part of a larger movement by women athletes to get their due. Wimbledon relented and started paying women far more years ago, Olympic women athletes are agitating for better conditions and pay, as are the women athletes of the national soccer team. And when women take a stand, we should note that they often win. In other words, the poor treatment poor conditions, and inferior pay turn out to be just that.
I'm willing to bet that the WNBA players win major concessions from their NBA handlers, that the league not only doesn't fold, but prospers, and we see that they were right all along.