DrCaleb DrCaleb:
The likely reason it failed is because like most DC movies, it sucks.
This is true. The only DC movie that should be considered excellent since Christian Bale quit as Batman has been Joker. All the others have been average-to-mediocre in quality. Even Wonder Woman IMO was merely OK. I didn't like Aquaman all that much because it was too long, bloated, and garish. They've wasted a lot of good talent, especially Henry Cavill, with a very "meh" cinematic universe. Harley Quinn might be all-that to the genuine fans and nerds but to the casual outsider audience she's probably still too obscure a character to justify having as a head-liner in her own movie. No slag at Margot Robbie but that's just the way it is.
Most of the Marvel movies haven't been that great either. Except for Avengers (starring me

) and several of the X-Men most of their films aren't worth going out of the way to watch twice. They're fun bubblegum but that's all. I know worshipping Stan Lee has always been a thing but not every character has to be dropping one-liners all the time. It's not a contest to see who can make the most yuks.
Scorcese was right. It's entertaining in it's own silly way but none of this should be mistaken for artistic cinema. Nerd-heads will explode in outrage at being told something to the contrary but, just like Star Wars, it's all just fluff and a time-killer.