Demand curve is same as Marginal Benefit curve? Demand curve is same as Marginal Benefit curve  [Source: Microeconomics by Pindyck &amp; Rubinfeld, Chapter 10, Section 5 - Monopsony]. I have only seen intuitive explanations for this statement. Can anyone prove it mathematically?
I am confused because for example is the curve is P = 10 - Q, then for Q = 1 to Q = 2, the total utility level changes for BOTH the first consumed product and the second one but the term &quot;marginal benefit&quot; seems to capture only the change due to second item consumed.
Nuance matters:
In the comments under 1muflon1's answer the quote given is


The demand curve represents marginal benefit. The vertical distance at each quantity shows the mount consumers are willing to pay for that unit. Willingness to pay reflects the benefit derived from each unit.


So the actual claim is not that the demand curve is the same as the marginal benefit curve, but that it represents it in some way. To be even more precise, the inverse demand curve represents marginal benefit. The demand and inverse demand curves are often conflated as these mappings are represented by the same graph.