I mean, the publisher seems to be pretty stupid, because...how did they figure that $250 million?

There are two entries in the Subnautica series, Subnautica and Below Zero. Subnautica has sold "over 5 million copies" at a retail price point of $30. So that's $150 million in gross revenue. For this back of the napkin math I'll assume that the "over five million" and the number of copies sold at a discount come out in the wash. 30% of that gross revenue is going to immediatley go to Steam or whatever other platform, so the company got $100 million in net revenue before their own expenses like rent and power bills gets at it.

I cannot find sales figures for Below Zero, but it sells for the same price point and I don't think it could have possibly sold more than Subnautica did, so let's figure another $150 million gross, $100 million net.

Subnautica as a franchise netted its studio ~$200 million across the launch of two games selling ~10 million copies.

And Krafton had agreed to pay out a $250 million bonus for reaching a certain revenue target in 2025, which they were on track to do given the announced early access launch.

Just to put them in the black for that bonus, Subnautica 2 would have to sell better than both previous games put together at a higher price, and that doesn't touch the purchase of the studio, operating expenses, or the dump truck of cocaine that must have been involved in these financial decisions.