>The "Chinese math" fallacy is only fallacious when it hides how difficult it is to steal a small percentage of a giant established market.
Which is what I was using it for.
>How exactly does the "fallacy" apply to Uber, a company that thoroughly understands how difficult it is to carve a big chunk out of entrenched competitors?
To clarify, that part is not the problem with the comment. That is a legit argument for why Uber can justify its valuation.
The problem is trying to amplify the persuasiveness of the argument by appealing to "small percent of huge = big". That deceptively makes the argument more appealing than it deserves to be, and is a lazy form of justifying a valuation. It plays tricks with human intuition on big numbers to (as you note) underplay the difficulty of getting a small number.
Hence why it's a "reach for my revolver" type situation.
Be careful not to equate "they have, independently of this argument, a good case here" with "therefore it's not the Chinese Soda fallacy to mention the percentages."