Ok, one more time for the Gipper. If that hedge fund manager/partner takes home 3 billion dollars and invests every penny beyond what he spends for necessities IAW his basic life style, all of that extra money is an increase in marginal utility. If that hedge fund manager/partner paid all of the money for necessities IAQ his basic life style then puts the rest of the money in a lock box earning less than had he invested it, he would suffer a loss of marginal utility. It is really very simple. Why are you trying to make it out to be difficult?
Maybe you can tell me what the actual effect on that hedge fund manager would have been if he had taken home 1.75 billion dollars less....
What would he have to do without.....
The marginal utility of money is constant.
In economics, the marginal utility of a good or service is the gain (or loss) from an increase (or decrease) in the consumption of that good or service. Economists sometimes speak of a law of diminishing marginal utility, meaning that the first unit of consumption of a good or service yields more utility than the second and subsequent units.
The concept of marginal utility played a crucial role in the marginal revolution of the late 19th century, and led to the replacement of the labor theory of value by neoclassical value theory in which the relative prices of goods and services are simultaneously determined by marginal rates of substitution in consumption and marginal rates of transformation in production, which are equal in economic equilibrium.
The term marginal refers to a small change, starting from some baseline level. As Philip Wicksteed explained the term,
"Marginal considerations are considerations which concern a slight increase or diminution of the stock of anything which we possess or are considering"
Frequently the marginal change is assumed to start from the endowment, meaning the total resources available for consumption (see Budget constraint). This endowment is determined by many things including physical laws (which constrain how forms of energy and matter may be transformed), accidents of nature (which determine the presence of natural resources), and the outcomes of past decisions made both by others and by the individual himself or herself.
For reasons of tractability, it is often assumed in neoclassical analysis that goods and services are continuously divisible. Under this assumption, marginal concepts, including marginal utility may be expressed in terms of differential calculus. Marginal utility can be defined as a measure of relative satisfaction gained or lost from an increase or decrease in the consumption of that good or service.
Thus it is understood that so long as the individual concerned actually increases the utility with a marginal increase such as making a monitary investment such that more money of equal purchasing power is gained, the marginal utility of money does not go down.
If you want to translate that to a good or service, letting N represent that good or service. If one acquires N x Y to the point that that the Y factor (Money) sits in the closet (the lock box)and is not used, that would indicate a marginal loss of utility.