Some speculative vehicles are not zero sum games because they have one or more of the following characteristics: they are an experiment in some technology or tool that can benefit all people, or the simple fact that they exist is useful, or they enable capital to be allocated more efficiently. Almost all speculative assets have the last trait, all currencies have the second trait, and right now as far as speculative assets go, only cryptocurrencies have the first trait.
When you say "benefit" you mean to get profit. But "benefit" can mean much more than that. The benefit of the invention of electricity cannot simply be attributed to the amount of profit made from it, or the amount used by the purchaser. It has a myriad of less tangible yet more impactful benefits, such as it helped humanity understand electromagnetism and it helped humanity get out of the mud. The same applies to new ways to abstract value. Would you say the concept of money has value beyond simply who has how much?