Both sides are wrong - it is not a zero sum game, but it is
Every election cycle eventually gets down to the one central point around which all societies revolve. After a while the peripheral distractions and deflections start to take their appropriate place - all the questions of personal integrity, experience, qualifications, hair style, stupidity and intelligence - become simply adverbs coloring the real active words:
Give and Take. Win and Lose.
All other verbs used in the rhetoric are euphemisms or synonyms of these four simple actions.
What will the putative president give me and what will he or she take away? Will I win or will I lose? In the end, people vote based on their own perception of these action verbs. Many stupid, corrupt and unqualified men have been elected president, because they struck the right balance between give and take for the right number of voters. At the same time, many of the most qualified and intelligent candidates of unassailable character have failed because too many voters thought they'd end up on the wrong side of the win and lose equation.
Verbs need nouns - nouns as subject and object of the action. The four nouns are: Me, Us, You, Them. All other words used in the rhetoric are euphemisms or synonyms of these four simple nouns.
And eventually, every candidate and their supporting parties comes to the most simple of messages. "My fellow Americans, if you vote for me, I will take from them (and give to you)." "Vote my way on Tuesday and you will win (and they will lose)." The entire campaign process leading up to the final simplification of the message - and the final decision the candidates want you to make - is only to define Us and Them; to define the currency of Give and Take; and to define the conditions of Win and Lose. Winning candidates ensure the question is framed as a zero sum game: whatever YOU lose (or give) is won (or taken) by THEM in equal measure - one for one, unit by unit.
Since the blossoming of industrial capitalism, there have only ever been two measures of win (take) and lose (give) - but there have been many measures of Us and Them. The successful candidate is always the one who best matches the teams - that is, who is on the We side versus who is on the They side - with the corresponding stakes of the game, and the appropriate conditions of victory.
The two measures of take (win) and give (lose) are always: Wealth and Power. It is in these measures that the concept of Zero Sum comes into play.
The "right" considers both Wealth and Power to be an ever rising tide that organically and naturally "floats all boats"; the "left" considers both Wealth and Power to be finite pools of resources that must be actively managed and distributed amongst the polity.
The right rejects the idea that Wealth and Power are interconnected; the left rejects the idea that Wealth and Power can be decoupled.
Both sides are half right and half wrong. Power is a finite commodity; Wealth is not. Wealth and power are absolutely intertwined, but not always inextricably.
The euphemisms for the two measures are myriad, and have included words like: Justice, Equality, Security, Jobs, Growth, Inflation, Taxes, Deficits, Law, Order, Rights, Progress, Future, Prosperity, Opportunity, Freedom, Liberty, Merit, Responsibility, Deserving (and Undeserving)... they all resolve to who has the money, who has the power; and who doesn't.
The conditions of Win and Lose are a little more fungible, but always get down to a measure that matches the selected euphemism for Money and/or Power. For instance, Jobs: In economically secure times, the conditions of victory associated with Jobs is qualitative: "Better, Higher Paying Jobs for Us." In economically troubled times, the condition is quantitative: "More Jobs for Us." Another useful combination in good economic times is Taxes, with victory defined as "Lower Taxes for Us..."; in bad economic times, the candidate will promise "Higher Taxes for Them..."
The final element of the equation is the definition of Us and Them. Who will win and who will lose? Who will give and who will take? Let's look at Taxes-as euphemism-for-Money-and-Power, and match it with the right definitions of Us and Them.
In good economic times, the right message will be: "Give lower taxes to the deserving, meritorious middle class men and women of this country who demonstrate all the qualities that have made this land great... We hard working, god-fearing, responsible men and women who have built this country have earned the right to keep more of what We make; to pass it on to future generations, so that Our kids have a bright, prosperous future. Take entitlements back from Them - the idle, irresponsible, undeserving who have an unfair advantage over Us, who have everything handed to Them without having to earn it."
In bad economic times, the right message will be: "Justice demands We take away unfair tax breaks from Them, the irresponsible rich with all the power who have made a mess of this economy... Give Their money to Us - the disadvantaged, disenfranchised who can't find good jobs - in the form of government stimulus jobs, unemployment compensation, and the assistance We deserve to live with some basic human dignity."
Both the left and the right agree on one thing: The Us and the Them are a Zero Sum game with only one goal: Our side wins only if the other side loses. This, in the end, is the fatal flaw of exclusive two party politics. It absolutely and inevitably leads to Us and Them, Win and Lose. It was this that the Founding Fathers most feared, for they recognized that a two party system could only ever lead to the state in which we find ourselves. Our system is structured for a binary result, for a zero sum answer - despite the reality that the questions are far more complex and nuanced than that.