Supposedly, 2/3rds (that is 66%) of the NBA teams lost money last year.
Why wouldn't there be more than 10-14 teams willing to miss the season? Why only around 33% and not all 66%?
Because the answer maybe is only 33% of teams are actually losing money.
Well, keep in mind that a lot of the teams that previously were losing money would now be making money under this deal. We're talking about approximately a $10 million per franchise shift per season. Teams that were barely losing money would now be profitable; I doubt they'd complain too loudly about that.
Also, of course, there are the owners who don't really care about money, as they see their franchises as a hobby / ego booster, rather than as a revenue maker.
When you look at those two factors, I'm surprised that as many as 10 to 14 teams would be willing to lose the season over relatively minor differences. If the owners can get their 50 / 50 split, I would have expected way more than 16 - 20 franchises to sign on.