I don't mean to sound trite but hasn't it pretty much been proven to be already?
Look at things like the Equifax situation. A competent team performing security reviews and fixing and maintaining things would cost money. Repeat for N data breaches. And that's just software security -- it doesn't consider even more serious cases like those of infrastructure failures (bridge collapses, levee failures, dams breaking etc.) that have more important consequences.
I agree with what I believe was the main point you were making which is that SEGA should not be excused here. I just think businesses have come to view competence as being expensive and so it's optional, and that this seems to be somewhat okay with people until it directly affects them.
In a just court, that argument would be thrown out. But courts aren't always just, unfortunately.
What a time to be alive.
Their inability to route that information to the right person should not be a valid defense or else incompetence becomes a business advantage.