At 1.5 million buys, they'd make wayyyy more than 40 million each. But Showtime does believe the fight does 1.5 million and they're willing to put up more money than DAZN.
No, Hearn agreeing to Joshua doing two fights on SHO PPV risks pissing off DAZN and Hearn can't afford to piss off DAZN when DAZN can cancel Hearn's deal with them.
And even if they could, you need to explain why Hearn refusing to do the fight on PPV to keep DAZN happy is going to cause DAZN to end their deal with him.

Comment