I'm guessing they have a lot of shares in the AI companies they work(ed) for, and they would like to pump their value so they can buy an even nicer carribean island than they can already afford?
Kokotajlo in particular is notable for being the guy who quit OpenAI in 2024 in protest of their policy of requiring researchers to abide by a non-disparagement agreement to retain their equity. In the end OpenAI caved and changed their policy, but if he was lying all along to inflate the value of his shares, it would have been quite a 4d chess move of him to gamble the shares themselves on doing so.
Kokotajlo gave up all his shares in OpenAI as part of his refusal to sign a nondisparagement agreement with OpenAI.