I don't buy it, they wouldn't even be producing Korean games with that mindset.
Also 30K out of 1M is not bad at all for a game like Stellar Blade?
The reason Sony is making games with Korean game developers is different from the reasons they're investing in Hero Project nations.
With Hero Project, they are trying to get in early for emerging territories to foster game development and encourage game productions which would build an audience interested in PlayStation-type gaming in those regions. It's a national effort with worldwide possibilities.
With Korean game deals, they're not necessarily interested in the territory; they're interested in the games.
Korea has a gaming market. It has for a long while. It also has some great and technologically advanced game studios. (And i would take a guess to say it also has a pay structure which is more forgiving to a publisher than an equivalent American or Japanese studio?) Also of note, it has a cultural style in its popular entertainment (...often heavily influenced by Japanese culture from decades prior, but i digress with a bit of race-sniping.) What it doesn't have is a robust market nationally to support a wide range of games, because online is dominant and a few whale-baits rule. So every once in a while, their talents spill out into the console space to make a play for greater global interest.
This happened with Kingdoms Under Fire and 99 Nights, this happened when MS bet on CrossFire and KartRiders (didn't quite pay off), it's happening now with Stellar Blade (big payoff, but to be seen if it can be capitalized on?), kind of happened when Sony accepted Genshin Impact (albeit that was a surprise blockbuster, also not handled directly by Sony and not necessarily in the PS mold), and it could spike in happening with the finance/tech/pop factor confluence that is making Korea a rising player in the global gaming market today.