By this logic couldn't you say that because ECommerce penetration is only 14% in the US then there's no reason for physical retailers like Walmart to expand online? Maybe I'm wrong but I don't agree with this point. Why wouldn't a business want to expand?
Also, I understand that you're trying to show the bear case here. But your calculations that you're basing your assumptions on you even stated "are probably incorrect." You made a lot of very interesting assumptions that none of us know could be close to reality or far from it. For example, you assumed people spending less than RMB 2k and people spending between RMB 2k and 7k was a 50/50 split. What if its a 10/90 split, or a 20/80. That would completely change the whole premise of the questions you would be asking. While completely making all of these assumptions, you are asking for others to come and argue against you with some "believable numbers." Again, maybe I'm wrong here and not trying to argue, but just trying to think through everything here critically. I'm choosing to believe that Alibaba's numbers have a high probability of being factual, and I think the incentives are way more in the favor of that assumption than yours. But again, maybe I'm wrong, we'll find out eventually.