Can someone explain to me why they believe the owners when having no substantiated evidence of these supposed losses?
They don't believe the losses are as large as the NBA claims, but they have provided "substantiated evidence" by submitting audited financial reports:
"The NBA has shared with the players' union audited financial reports for all 30 teams which unequivocally demonstrate why Mr. Hunter favors the expiring agreement and why it does not work for us," spokesman Tim Frank said.
https://sports.espn.go.com/nba/news/story?id=6243850
So, establishmentarians, why do you believe the owners claims with no real evidence?
Well, I haven't seen the evidence, but apparently the NBPA has. They saw enough to immediately, before negotiations really began, offer up a 3% concession of BRI worth $100 million a season. There is NO DOUBT that the NBA has been losing money. They players didn't offer this concession out of the goodness of their hearts. I don't think it's wrong that the players are trying to get as much as they can, but most would agree that the owners have all the leverage right now. Meanwhile, we have NBA players tweeting that 1/2 the revenue is going into owners pockets as if they have no other employees or expenses to run the league.
No, fans don't go the arena to watch the owners. However, the players don't have to pay the salaries and expenses of thousands of other employees, pay for the arena, player's travel expenses, player's food and hotel expenses, medical staff, insurance, etc. That all comes out of the owner's "cut". And apparently, that cut is lower than all the other expenses combined.
I understand both sides. The players want to keep as much money as they can, and the owners want to end their losses and start making some profit. You can see each side's point, but the owners have the leverage. Why do they have the leverage? Because they are operating at a loss, and the player's are all making a profit.