The article claims/repeats the claim that this cost valve $250 million, but I don't see how. If the leaked version wasn't very playable the damage can't come from lost sales
yeah that is just "let's throw random numbers to victimize ourselves even more". I don't think a lot of people downloaded the unfinished source code, compiled it, played the game and never bought the conplete game. The worst that happened were people making memes with some 3d and graphics assets which didn't cost anyrhing to Valve. Quite the opposite it was free advertising.
I imagine that if I branched out in gaming it would have been a nice bonus, it's not everyday you get to see the competition's code. I suppose they lost in opportunity cost to license their thing, a bit ?