They have majority of the attention and market cap. They have runway. And that part is the most important thing. Others don’t have the users to grand test developments.
XAI has Elon's fortune to burn, and Spacex to fund it.
Gemini has the ad and search business of Google to fund it.
Meta has the ad revenue of IG+FB+WhatsApp+Messenger.
Whereas OpenAI $10 billion in annual revenue, but low switching costs for both consumers and developers using their APIs.
If you stay at the forefront of frontier models, you need to keep burning money like crazy, that requires raising rounds repeatedly for OpenAI, whereas the tech giants can just use their fortunes doing it.
Ok, others have more runway, and less research talent.
OpenAI has enough runway to figure things out and place themselves in a healthier position.
And come to think of it, loosing a few researchers to other companies may not be so bad. Like you said that others have cash to burn. They might spend that cash more liberally and experiment with bolder riskier products and either fail spectacularly or succeed exponentially. And OpenAI can still learn from it well enough and still benefit even though it was never their cash.