Well-being refers to several aspects of life - physical, emotional, social or financial. Though correlations between them exist, these aspects may not always parallel each other. For instance, an individual might be financially secure, but emotionally unstable. This notion makes me question the effect of early attachment on future well-being. With such a broad definition, it seems unlikely for each aspect of well-being to be influenced by attachment. Nevertheless, one may consider a correlation between emotional well-being and attachment likely, due to a gradual emotional development during early life stages.
I like how you questioned the actual relationship between attachment and future well-being. I agree in that early attachment does not necessarily create a good outcome or a bad outcome. General well-being is definitely what you make of any situation and attachment may only affect a child's relationship with their caregiver. I also agree that attachment is more likely to influence your emotional well-being rather than your financial well-being and that a certain type of attachment may create an emotional response or future outcome.