An arbitrator ruled in Netflix’s favor in a high-profile dispute between the streaming giant and the Hollywood director Carl Erik Rinsch over a science-fiction series that never aired, awarding the company nearly $9 million in damages.

Mr. Rinsch had sold Netflix the television show, “Conquest,” near the height of the streaming boom in 2018, but he never delivered any episodes. Netflix had to write off the $55 million it had spent on the project — a fiasco that became a symbol of the era of profligate spending that Hollywood studios are trying to put behind them as they focus on increasing profits rather than simply adding subscribers.

Netflix canceled the development of “Conquest” in early 2021 after Mr. Rinsch’s behavior turned erratic. In texts and emails to Netflix executives, he claimed to have discovered Covid-19’s secret transmission mechanism and told his wife, a producer on the show, that he could predict earthquakes and lightning strikes.

After Netflix informed Mr. Rinsch that it had decided to stop funding “Conquest,” he went on a spending spree with the show’s remaining production money, living out of five-star hotels in California and Spain and buying a fleet of luxury cars and high-end furniture. He said the cars and furniture were props for the show, but the arbitrator, the former Los Angeles Superior Court Judge Rita Miller, ruled that none of the purchases were necessary for the production, according to a copy of her ruling reviewed by The New York Times.

Mr. Rinsch initiated the arbitration, alleging that Netflix breached their contract and owed him at least $14 million.

Ms. Miller, however, ruled that Mr. Rinsch was at fault. The $8.78 million that she awarded Netflix corresponded to the amount of production money that she said Mr. Rinsch squandered. She also awarded Netflix control over the “Conquest” footage, which the director had kept in his possession until now.

Mr. Rinsch didn’t respond to requests for comment.