Uber makes revenue from customers. Not all investments are good investments but the fact remains that businesses have non-investor participants from which the goal is, in the full course of time, to extract profits. While specific equities may be bad investments, equities in aggregate are positive-sum because investors aim to extract profit from non-investor participants. They may fail! But that doesn't change the goal.

This is not the same as a cryptocurrency which relies solely on later investors to create returns for earlier investors. There are no non-investor participants from which profits can be derived, period. Cryptocurrencies are in aggregate either zero-sum (best case, PoS) or massively negative-sum (worst case, PoW, especially Bitcoin).

This represents a pretty fundamental misunderstanding of, well, investing.