Incomes don’t follow a bell curve, so the choice of mean income is a red flag to me. Imagine you had 9 citizens making 100k and one billionaire, the mean is now 100,090k.
Relatedly, being in the bottom 10% doesn’t necessarily mean the same thing in these different countries, in some of them that might not be below the poverty line so it’s comparing apples and oranges.
I doubt anyone you are talking to is opposed to all human rights, that sounds very much like a straw man statement. Reasonable people can disagree about whether any particular right should be protected by law.
The reason is simple: any legally-protected right you have stands in direct opposition to some other right that I could have:
No right is ever meant to be or can be absolute, and not all good government policy is based on rights. Turning a policy argument into one about human rights is not generally going to win the other person over, it’s akin to calling someone a racist because of their position on affirmative action. There’s no rational discussion that can be had after that point.