What do you mean?
I mean that men who can, by their own efforts, financially support several wives and dozens of children are few and far between. Since the states do not recognize plural marriage, the soi-disant wives are legally unmarried mothers and eligible for welfare and a host of other taxpayer-supplied benefits. The teenage boys driven in large numbers from polygamous sects are also burdens on the state.
In many ways, the financial situation of “polygamous families” parallels that of the serial hookups and multiple baby-daddies of the inner-city poor. Both “lifestyles” are made possible by government handouts.