“He who is not contented with what he has, would not be contented with what he would like to have.” - Socrates
Note this assumes the base level of have. There are studies that happiness does in fact go up quite linearly with increase of income while your basic needs are not met. However, once the basic needs are met the relationship between income and happiness plateaus and takes quite a logarithmic shape. But for those that do have the basic needs met, it is paramount to work on mindset of being content now.