That link shows Gabe Newell's estimated net worth, but does he have have 100% ownership of Valve? The Valve Wikipedia page shows his ownership as ">50%" [0], but isn't more specific.
> Valve was valued at $7.7 billion in May 2022 based on Bloomberg calculations and discussions with Michael Pachter, a Los Angeles-based analyst at Wedbush Securities. This value has been adjusted for the performance of the Russell 1000 Electronic Entertainment Index since then.
From the link I posted above.