Justice league is the foundation and the whole point of the DCEU universe, it ws expected to make near 1,5 billions just like the 2 avengers movies plus create hype to make DCEU big as MCU and make 2,5 billions every year just like them.
They lost the chance to almost double the money the produce per year with movies,
That the biggest disaster in WB history, they're paying 300 millions when they expected a profit of near 900 millions right now they will have 1,2 billions less than they planned.
Also JL 2 and 3 are gone forever, that's more 3 billions that will never came and now investors faith in DCEU is broken.
Hack snyder did more damage to WB in a couple of years than Disney could ever hope to do in a couple of Decades