Apple, along with a bunch of upstream suppliers, brings together some glass, some plastic, some metal, and create an iPhone out of it. The value of an iPhone is greater than the value of the raw materials. Thus, it's a positive sum game. Same goes for owning a stake in Apple the company.
One person buys a Bitcoin that another person sold, which is zero sum. But miners burned real energy paid with not-Bitcoin to process it, thus value exits the system. Thus it is negative sum.