Elon Musk was reportedly 'furious' at ChatGPT's popularity after he left the company behind it, OpenAI, years ago

• Elon Musk was reportedly mad when OpenAI's ChatGPT made its splashy debut, Semafor reports.

• The OpenAI cofounder tweeted that the company became a "ruthless corporate monopoly" after he left.

• Musk's frustrations come years after a reported falling out with OpenAI's CEO Sam Altman and other cofounders.

Twitter CEO Elon Musk was reportedly "furious" when OpenAI's impressive chatbot ChatGPT launched last November and ignited discussions about it being a threat to Google, sources familiar with the matter told Semafor's Reed Albergotti.

Musk's frustrations around ChatGPT come years after the OpenAI cofounder reportedly fell out with the company due to disagreements over who should lead it, and Musk's feelings OpenAI was falling behind Google.

Semafor reports that in early 2018, Sam Altman and other OpenAI cofounders rejected Musk's proposal to run the company — a nonprofit at the time — on his own in an attempt to beat Google, which created a fissure between Altman and Musk. As a result, Musk stepped down from OpenAI's board and pulled future funding, per Semafor. More than a year later, OpenAI became a for-profit entity.

But OpenAI eventually proved quicker than Google at launching a generative AI chatbot. ChatGPT came out near the end of 2022 to great fanfare, quickly crossing a million users and even resulting in a reported "code red" issued by Google management.

In the months following its launch, Musk took to Twitter to express his frustrations over OpenAI.

In December, Musk tweeted that he restricted OpenAI's access to Twitter's database — which he reportedly agreed to before he took over Twitter, per Semafor — after he learned it was being used to train its GPT language model.