People who oppose any sort of property right infringement believe that what they own, they own, because they have acquired it in totality through their own actions and means, and thus they have zero obligation to share it with anybody else.
This only applies if what one owns really is what one owns by ones own means. But this is almost never true. Almost everything you own, you own because somebody else altruistically felt that you should own it, or, even if it were not an altruistic gift, this somebody else may have given you something and expected something in return. Therefore, the assumption that you have zero obligation to share that which you were given by somebody else no longer holds (at least morally).
For example, pretty much everybody in a civilizied country has received a public government-funded education. This education is not some naturally existing feature of the world, somebody gave it to you and expected something in return, namely that you get a job and pay taxes so that the society kan keep on functioning. Therefore, if you, using your education, acquire some property, you do owe some of it to the government.
So my question is, why don't people who believe in ultimate property rights not move out into the woods? Then they can own whatever they want to own. But if they live in a society, they must accept they have entered a contract, and that contract implies that there is a debt to be paid.