Hmm, we may have differences in philosophy here. That's good. Based on the premise above it's senseless to buy any weapon and practice with it for self defense. If anybody does, it's ok to get a bad quality product since the odds for self-defense are incredibly slim. But, I think those odds are different for different people. So, I think our disconnect is my odds for the need for self defense are more likely than yours. In any case, a beauty of knives is how multi-functional they are. One of those functions is a weapon.
You're worried about a knife breaking. A knife isn't going to break unless it receives a a lot of hard use, and a knife that you carry solely for self defense will NOT get a lot of hard use(and the fact of the matter is, it will most likely never get used, unless you're either a criminal or a fool doing something you shouldn't be, like provoking fights). And even if you DO have to use the knife in defense, it's not going to break from stabbing someone.
Of course, most people will point out that a knife is a terrible weapon for self-defense anyway, but if you want to carry one for that purpose(and that purpose alone), the Chen one isn't going to give you any problems.