My point exactly - if it would have made a lot of money compared to the investment, then Sony would certainly try to capitalize on its success.
But now we're talking about a lot of money made? I thought the question was whether they made money, period. That's my point. I don't think it made them crazy amounts of money. Was it profitable? At 1 million copies, I suspect it was, yes. Profitable enough that the IP must be kept alive no matter what? Probably not -- Sony has no lack of IP. If we're using Gears of War as a measure for success, then almost every single HD title fails.
In contrast, look at Uncharted. It also supposedly had a budget of 20 million. It also sold over a million. But we have a sequel lined up for that game. We also have claims from Naughty Dog that Uncharted was, indeed, profitable. They could be lying, naturally. But my point is these 'a game must sell x many copies to succeed' is usually based on huge generalizations and a lot of inaccurate guesswork.