Why do you think it's important to estimate how much you will need in

retirement?

It's important to estimate the amount needed for retirement because if you do not have enough money for bills, food expenses, and extra for emergencies for the rest of your life, you will have to go back to working. Which will be harder because most companies want younger people working instead of older. It also depends on your field of education base for what people they are looking for. So you would want to have enough money for the rest of your life. Which you would make an estimate for a total of your bills and monthly food expense in addition to that emergency so you don't run out of money for 20-40 years