Capitalism measures maturity by independence, and independence comes from the paycheck.

I measure maturity by how old a person feels in the presence of their parents: the ability to manage their own emotional energy and control their own behavior.

(Which introduces some tricky dynamics. For example, some people might be very mature, but appear immature because they are dealing with complicated parents. Others appear very mature because their parents do all the emotional work. Away from their parents they turn into children.)