Your obvious answer follows from a specious argument. You assert the notion of "property" as if it were a clear and well understood absolute. However, that is far from the truth.

For example, almost all land has been taken by force at some point in its history. I own a house, but the land it was built on is almost certainly stolen property (by your "obvious" notions of property).

For another example, when I get paid, some of that money gets paid as taxes. That's not something I agreed on, by your ideals, I should be able to opt out. But, my property only exists because of the work of the government to protect it, and that work came with an implicit reciprocal agreement that it would remain as part of my country. The land I own is, in a sense, also owned by my country. By removing my land from my country I would be breaking the implicit agreements formed when it was first entered into the land registry. The same goes for other things besides land, in particular, the companies I work for are registered and protected by my country. Corporations are abstract concepts, they can only exist by being built on a complex shared legal framework. Again, if you own or want to start a company you might want to opt out, but everything that got you to the stage of being able to opt out is built on implicit social agreements between you and your nation.

When I earn money, I do not create value in a vacuum. Everything I do relies on the wider society. I'm not just talking about the obvious things like roads and the police. Social structure itself is vital to enable my ability to earn money. I thrive because I live in a relatively peaceful society with a shared language I can communicate in, with shared cultural norms that make life comfortable. Those things are shared property, belonging to society a whole, for which we all owe a debt and a reward.

The very notion of money itself is a social construct. The faces on your money belong to your government leaders. Money only has value because we all agree that it has value. Otherwise it is just a high score in a very boring game. In a sense, all money belongs to all of society. Everyone owes a debt to everyone else for the simple fact that we don't have to barter. You might think this sounds ridiculous, but this idea of ownership exists and is prevalent. Governments print and destroy money, they manage circulation, they control inflation. In a general sense, the currency belongs to the government. In an even deeper sense, a large part of what people spend their money on is related to social structure. People buy material things for the social status imbued in them and they consume entertainment that relies on a shared cultural understanding. Every movie you watch has been informed by hundreds of years of theatrical and cinematic progress that is owned by no-one and everyone.

You can't have an absolute fair notion of property. It doesn't exist. Every piece of land has been stolen at least once. Everything else was created through some level of coercion. The distribution of wealth has never been fair. It wasn't fair when I was born, and so the requirement for me to earn a living (because I was not born rich) is an unfair coercion. Also, it wouldn't even be possible to be fair if we started fresh on a new planet. Absolute fairness requires isolation from all implicit social contracts, which is impossible for humans to do.

Most importantly, absolute fairness based around the single ideal that no-one can take someone else's property would be an awful and inhumane way to run a society. The people who have more property then others have a way of convincing themselves that they deserve it. Which is an argument that can be used to justify all manner of horrors. On the other hand, if we put aside ideals and look at what practically makes a better society, under any reasonable set of measures, reducing income disparity is a good thing.

Society is a set of implicit and explicit rules that form a game. Money and status are like scores of the game. If wealth accumulates too much in one person, that does not mean that this person deserves to live like a king while others needlessly starve. It means the rules of the game are exploitable and need to be adjusted. Not everyone is a master strategist, not everyone has the abilities to get rich. In the future, most people won't even be able to get a job. Those people don't deserve to suffer just for being normal humans. The people who can do useful work (and I include myself in here) don't especially deserve to be saved from suffering just by virtue of having been born with unusual skills.

Society can easily reward those who work hard and have valuable skills to contribute. These people can be made very comfortable. Society can also look after those people who do not have the skills to become wealthy, who are not suitable for positions of power. There is enough to go round. There will be even more in the future. It's possible for us to have a peaceful, low-crime, happy, healthy society where those who earn a lot have to put up with sharing some of it as the cost to them for living in such a great country. Or, we can ruin ourselves over an impractical ideal of property that, at root, is like a child clinging to a toy and shouting "mine".