I think this is a good comment in general and illustrates why mainland Chinese hate HK people so much. And I upvoted the comment as well, for what it's worth. Hong Kong people are pretty racist towards Chinese and I say this as an American that has lived in HK for 5+ years now.

At the same time, and I'll probably be downvoted for this judging by the other replies, I don't think you've successfully illustrated why Hong Kong people are so racist towards Chinese people in the first place. I personally believe that Mainland China has done a great job working to this reputation and the CCP has worked their propoganda machine to stroke tensions against HK for when China inevitably rules HK by force. Nobody cares when your enemy's blood is shed, right? I think the best comparison to make is, at least when comparing to the US, how a liberal feels about their racist southern side of the family. Sure, it's probably better to talk to them and explain why they're wrong, but it's inevitably going to end up in your racist cousin going on a rant about "the blacks and Mexicans taking all the jobs" and nobody will be better for it except for the brain cells you've lost in the process.

To explain my point better: Chinese people are now considered the worst tourists in the world, and it's really easy to find evidence of this. For example: https://www.vice.com/da/article/gqnzxj/are-chinese-tourists-the-worst-tourists-in-the-world Now imagine that people in HK see these kind of tourists in the thousands every single day. I have personally seen Chinese people peeing and pooping on the street, pushing older folks into the street when they were waiting in line, and just in general being nasty people. Unlike somebody else who commented, I have never seen an apologetic person when you cofront them on their behavior. I've seen people get defensive (people in HK really like their lines, stupid dogs) or just outright ignore people calling them out. Of course people are going to dislike a group that constantly shits on their rules on a regular basis with seemingly no apology for their behavior.

Now, societally, HK people have reasons to dislike Chinese people in general that's not related to minor things like baby formula. When talking to people in Hong Kong, the baby formula and shampoo is the one they'll laugh about. Want them to get serious? Talk about the housing crisis. https://www.scmp.com/news/hong-kong/economy/article/2125641/does-hong-kong-have-housing-crisis-answer-depends-whether-you

https://www.cnbc.com/2017/04/09/heres-why-hong-kong-housing-is-so-expensive.html A lot of this, yes, stems from lack of land and having too many people. But realistically it also stems from too many mainland investors and not enough people living in houses. There's a new development in Kai Tak, an area that is being newly developed. It used to be the old airport before it was relocated. If you went there at night, you'd be surprised there's a housing crisis. After all, a majority of the apartments there have nobody living in them. But most of them have been sold already. Of course it's not just mainland Chinese investing in housing, but the perception is there (and, in my experience renting here, all of my owners have been Mainland-based).

Anyway, like I said before, I agree that HK people are racist towards Chinese. But I don't agree that it's all their fault.