In a surprising turn of events, renowned directors Kevin Costner and Francis Ford Coppola have found themselves in a major slump at the box office with their latest ambitious films. While the summer box office has seen success with hits like "Inside Out 2" and "Deadpool & Wolverine," Costner's "Horizon: An American Saga" and Coppola's "Megalopolis" have fallen flat, leaving audiences disappointed and industry experts scratching their heads.

Both Costner and Coppola spared no expense in bringing their vision to life, with each project costing them a staggering $100 million. Unfortunately, the results have been far from satisfying, with these costly ventures acquiring the status of expensive boondoggles.

Just this week, 85-year-old Coppola released a new movie trailer for "Megalopolis," a $120 million epic centered around the turbulent rebirth of a city. However, this desperate attempt to generate interest backfired when it was discovered that the trailer included fabricated quotes from past reviews. Instead of creating buzz, this move only added to the growing list of humiliations "Megalopolis" has endured.

Coppola's passion project, which he has been working on since 1977 and even funded in part by selling a piece of his wine business, failed to impress critics and struggled to find distribution after a disappointing premiere at Cannes. The film's reception only highlights how much of a colossal waste of time and resources it has become.

In contrast, Costner's "Horizon" has already hit theaters and met a similar fate. The actor conceived the project as a sprawling, four-part Western, envisioning it as the "Game of Thrones" of the Old West. However, the film's debut at Cannes was met with indifference and derision, and domestic audiences were not much kinder. One critic, who gave the film a devastating one-star rating, declared it a bloated ego trip and expressed no desire to commit any more time to the tedious experience.

"Chapter One" of "Horizon" managed to gross only $34 million, a disappointing figure given the film's ambitious scope and Costner's involvement both behind and in front of the camera. As a result, the release date for the second entry has been scrapped altogether.

While their dedication to originality is admirable, these passion projects from Costner and Coppola are widely regarded as acts of foolhardy arrogance. Despite the directors' belief in their respective visions, history is likely to remember these projects as expensive missteps rather than groundbreaking works of art.

In the world of cinema, even renowned artists like Costner and Coppola are not immune to failure. The box office flops of "Horizon" and "Megalopolis" serve as a stark reminder of the unpredictable nature of the industry and how even the most celebrated filmmakers can stumble from time to time.