80 people and how long did it take to develop?
Let's say it took 4 years.
80 people in Finland. Let's assume they had 65 people year 1, 70 people year 2, 75 people year 3, and 80 people year 4 with an average salary of 65K dollars.
That would be about 18.8 million dollars. Let's round that up to 20 million dollars. Let's add an extra 5 million for advertising and publishing and porting to PC.
That's 25 million dollars.
Let's say the game sold at an average of 50 dollars and we know it sold 560K copies by July 2021.
That would have been 8 million dollars in less than a year. The game would almost certainly have broken even, even without the PC release, not to mention the gap filled on PS+.
There is a reason why Sony bought Housemarque AFTER Returnal launched. One the game was almost certainly a success (not an unmitigated failure) and they probably see the promise in potential in the studio to reach another level like they've done with many of their other studios.