Why would this spoil the milk? Why is it called "sponging"? The middle class safety net (something I grew up without) is one of the greatest sources of freedom

Why would this spoil the milk? Why is it called "sponging"? The middle class safety net (something I grew up without) is one of the greatest sources of freedom and investment generally available. Multi generational homes and properties are historically pretty normal and a net family positive for holding onto wealth. For example: https://www.middleclasspaas.com/ https://www.middleclasspaas.com/