To elaborate, it's Satan's MO as described by a person. Since ipso facto, Satan, conceptually described by a person, acts solely against each individual's well-being, the poem is meant to describe this reasoning as detrimental to the individual.

So to respond to your question, I do disagree with "Satan's" point.

It is clearly in the interest of an individual to keep all of what they are given, rather than to spend a portion simply to lower the portion given to another.

Along the same train of thought, I would say, "The least of us can achieve greater heights when lifting each other up, than the greatest of us can by pushing each other down."