Assuming that you're asking why we need a relatively fixed quantity of money, then you need to consider what happens to the value of the money in our savings ac

Assuming that you're asking why we need a relatively fixed quantity of money, then you need to consider what happens to the value of the money in our savings accounts, wages, pensions etc when new money is created. And secondly, by what means or effort is this new money created? Is it done fairly (i.e. through performing work of equal value) or is it created to the advantage of those having the power to create it (therefore making them unjustly even more powerful)?