By Dan Weil Households with income under $20,000 saw their earnings increase by only one-third of their cost of living increase in 2021. It has been said that it’s a lot easier to become rich by starting rich than by starting poor. That has now been confirmed by a Penn Wharton Budget Model report. It showed that employed households with income under $20,000 saw their earnings increase by only one-third of their cost of living increase in 2021. Their median increase in costs totaled $1,837 for October, November and December of last year, compared to a $578 increase in earnings. At the other end…