There really has to be a balance here. I am youngest of six with many "honorary" aunts, uncles, grandmas and grandpas around. We were not rich but I darn sure never went wanting for food, clothes or shelter. I dearly love my extended family and next of kin. And perhaps of no consequence I was adopted.
But here is the rub. Close extended family creates a dynamic. I am not at all speaking of a lack of love here or any intentional negative behavior. The dynamic for the younger siblings is a lack of import in family matters. Things are done for the betterment of the tiny tribe. Resources and energy are spent on things important to the group as a whole and the younger ones are but tag a longs. This is not always healthy for the development of things like fiscal responsibility and leadership qualities.
But in my opinion the love conquers all. The financial stability is helpful but not essential. In fact it seems to me that really hard working folk that just get by kind of ingrain a fiscal and work ethic value that can benefit the children forever.
And perhaps one of the most enduring gifts of living with a large extended family is a sense of security. And that allows a child to worry less about failure and focus more on success.