Marginal utility

Marginal utility is a concept from economics that describes the change in utility from consuming more or less of a good or service. Economists sometimes speak of a law of diminishing marginal utility, meaning that consuming the first unit usually has a higher utility than every other unit. When the number of units that are consumed increases, their marginal utility decreases.
The more we have a commodity or a service, the less we want to have more of it.