Tesla’s CEO financially backed the maker of the artificial intelligence chatbot ChatGPT when it was founded in 2015. At the time, OpenAI was a nonprofit. Today, OpenAI—which switched to a hybrid “capped profit” model in 2019—has a private valuation of about $30 billion and Microsoft as a major investor.

On Wednesday, Musk tweeted, “I’m still confused as to how a non-profit to which I donated ~$100M somehow became a $30B market cap for-profit. If this is legal, why doesn’t everyone do it?”

Legal and financial aspects aside, the mercurial billionaire worries about the dangers of artificial intelligence. When A.I. expert Max Tegmark, tweeting on Wednesday night about the potential dangers of the technology, wrote, “An unregulated race to the bottom will end badly for the human race,” Musk replied, “I agree!”

At the time Musk donated to OpenAI, it wasn’t Microsoft on his mind, but Google, which had a significant lead on the A.I. front. As he tweeted last month:

“OpenAI was created as an open source (which is why I named it “Open” AI), non-profit company to serve as a counterweight to Google, but now it has become a closed source, maximum-profit company effectively controlled by Microsoft. Not what I intended at all.”

In its founding statement, the then-nonprofit OpenAI stated, “Our goal is to advance digital intelligence in the way that is most likely to benefit humanity as a whole, unconstrained by a need to generate financial return. Since our research is free from financial obligations, we can better focus on a positive human impact.” 

In 2018 it laid out some principles in a charter, writing: “OpenAI’s mission is to ensure that artificial general intelligence (AGI)—by which we mean highly autonomous systems that outperform humans at most economically valuable work—benefits all of humanity.” It added, “We are committed to providing public goods that help society navigate the path to AGI.” 

The A.I. race between Microsoft and Google intensified this week: OpenAI launched GPT-4, a more powerful successor to ChatGPT, and Microsoft said the new version was powering its Bing search engine (a direct rival to Google) and will soon show up in its Office apps. Meanwhile, Google announced upcoming A.I. features for its Workspace apps, including Gmail and Docs, and it’s now refining Bard—a ChatGPT rival—before wider release, while some employees test a more powerful “Big Bard” version, according to Insider.

Earlier this month, Musk suggested at a Tesla investors day event he had some regrets over his role with OpenAI: “I’m a little worried about the A.I. stuff. We need some kind of, like, regulatory authority or something overseeing A.I. development. Make sure it’s operating in the public interest. It’s quite dangerous technology. I fear I may have done some things to accelerate it.”

Fortune reached out to OpenAI for comments but did not receive a reply.