Zero-Sum Game does not imply there are winners and losers, it says there can be only as much money gained as there is invested. With Stocks you have the company itself that can use a high stock price to finance the business which is creating actual value. Therefore you have external value that can come into the equation making it a non Zero Sum game.
Even though you have similar mechanics in Crypto where a high price can strengthen the infrastructure of a coin, there is rarely any additional value created. Hive has the added value of the shared information/entertainment/art that you can find on the chain, but hive is a rare case.