But that just pushes the question one layer of abstraction deeper. Why would that person be willing to buy Snap shares from you at any price?
On a long enough timeline, you have to believe that Snap will either disburse dividends, be acquired by another company or find some other way to convert ownership into actual cash.
They would buy because they believe they can sell it later at a higher price, based on the belief that other people want to buy $SNAP and will drive the price up.
I'm not avoiding your question—I agree that it should be based on underlying value—but that seems to be the only reason to buy $SNAP
On a long enough timeline, you have to believe that Snap will either disburse dividends, be acquired by another company or find some other way to convert ownership into actual cash.