I don't see how people can call Sony stupid for calling their product unhackable. Nintendo have done the exact same thing with their newest handheld. And yet we still don't have a hacked 3DS.
Now I know Nintendo isn't the same as Sony, but they're both gaming companies with products that have equal potential of being hacked.
And before we get into a discussion of who's responsible, let me say this, even if I might be wrong, in the clearest way my mind voices it to my concious: The hackers are faulty of robbing information that is illegal to obtain or sell, and have robbed it through illegal means (breaking laws and the PSN EULA). The company known as Sony is faulty of not providing adequate protection to its users at a time where the protection of the said product was being taken apart, for better or for worse. The users of Sony's services are retropectively at fault for trusting in a company that has flaunted a product with more features than it actually has, and entrusted various types of personal information through the EULA to the company. The EULA, in turn, is at fault for storing these kinds of informations on a server in the first place (type of TV used, disc inserted, almost all actions done on the product, etc.)
Rinse and repeat, and you have an evil circle based on what I described above. I think that the fact that all points lead to each other here (A->B->C->D->A->ad infinitum) is what frustrates people the most here: Everything is chewing down the users initally offered services. We can expect the company to rise again and break the evil spiral, as it is, but at the cost of a lost fanbase.
Another thing I noted today: I looked at Sony's stocks, ranging from the 20th to today. It seems the worth has dropped from ~30 USD to ~28 USD. Make what you will of that fact, but it doesn't look too great, if you take it from an economical standpoint.