Though there is often a correlation it is hard to prove causation between attachment and well-being. This is because there are many other factors including environmental factors that cannot be measured.
I agree, although there is correlation between attachment, socioeconomic status, and well-being, I would not say there is enough evidence to prove anything. It is even a steryotype for rich kids with great parents to be rebels, and kids with alchoholic parents are often less likely to become alcoholics because of the things they have grown up through. This correlation looks good on paper but in reality doesn't really mean anything.
