Mark Zuckerberg’s former top AI scientist explains why he left Meta

Yann LeCun, one of the most influential figures in artificial intelligence (AI), has opened up about his sudden departure from Meta. 

Speaking to the Financial Times, LeCun said his exit followed months of growing tension with CEO Mark Zuckerberg and changes in how AI work was being managed inside the company.

LeCun spent more than ten years at Meta (formerly Facebook), serving as chief AI scientist. 

During that time, he enjoyed wide freedom to pursue long-term and experimental research, often without pressure to quickly turn ideas into profitable products. 

He described the early environment as one with generous resources and few financial limits.

That culture shifted after the release of ChatGPT in late 2022, which sparked intense competition around AI chatbots. 

Zuckerberg pushed Meta to develop its own large language model, later released as Llama. LeCun agreed, but only if the technology remained open source, a move that earned praise from AI researchers worldwide.

However, LeCun said the pressure to speed up development hurt innovation. He pointed to the poorly received Llama 4 release last year, blaming rushed timelines and a focus on “safe” ideas. 

He also cited friction with rising leaders, including Alexandr Wang, which reduced his independence.

Beyond internal disputes, LeCun said he believes large language models alone cannot deliver truly advanced AI.