There is a big difference between being zero-sum and the sum being zero. A zero-sum game cannot end with any other outcome but the sum of zero. Non-zero-sum games can end with the sum of zero but can also end with other sums. This last part is what makes capitalism not zero-sum, even if in practice the sum is zero (which it isn't but that's a separate point).
I focused on zero-resources-needed services because they're the easiest example. They don't make much of the overall economy, but they do exist - tutoring, standup comedy, basic massage to name a few. Because no resources are used, you don't have to quantify the value to prove the sum is positive, you just need to prove the service isn't completely pointless. A proof for services that do use resources is also possible, but far more complicated and requires quantification of value, which is always a very contentious topic in and of itself. Like, you already contended it before I even invoked this concept, that's how contentious it is.
Externalities exist, sure. And are often omitted in pro-capitalism arguments, sure. But to argue that externalities make capitalism zero-sum is to argue externalities always exactly match whatever value was gained by capitalist transactions. Which is even harder to prove than the already dubious argument that externalities are larger than the value of capitalism.
I only brought up GDP to highlight that services are a big part of modern economy, so any model of economy that assigns no value to services is a wrong model, because it will not match the actual flow of money within a real world economy. I strongly believe models ought to be useful.
I focused on zero-resources-needed services because they're the easiest example. They don't make much of the overall economy, but they do exist - tutoring, standup comedy, basic massage to name a few. Because no resources are used, you don't have to quantify the value to prove the sum is positive, you just need to prove the service isn't completely pointless. A proof for services that do use resources is also possible, but far more complicated and requires quantification of value, which is always a very contentious topic in and of itself. Like, you already contended it before I even invoked this concept, that's how contentious it is.
Externalities exist, sure. And are often omitted in pro-capitalism arguments, sure. But to argue that externalities make capitalism zero-sum is to argue externalities always exactly match whatever value was gained by capitalist transactions. Which is even harder to prove than the already dubious argument that externalities are larger than the value of capitalism.
I only brought up GDP to highlight that services are a big part of modern economy, so any model of economy that assigns no value to services is a wrong model, because it will not match the actual flow of money within a real world economy. I strongly believe models ought to be useful.