See the more comprehensive detailing of this subject in this newer blog post:

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Software intellectual property is licensed and not sold, but software licenses and the instances of software they represent are sold and become the property of whoever buys them.

While purchasing a software license does not give the purchaser ownership of the intellectual property of that software, a software license itself is a personal property, to which a nations' laws of property rights apply, which grants an instance of a software, which a person may operate how they wish. But that doesn't include interfering with online services which the software may work with, or distributing modified software, which is duplicating the software which a license grants an instance of.

A software license's terms are as they were at the time the license was acquired. The acceptance of that license is a legal contract, governed by bartering laws, amongst others, and the license is a personal property, and one side cannot change the terms of that contract or the identity of the property, unilaterally.

All this does not mean that software-license issuers necessarily present the situation as it is any more than a prosecutor in a court of law argues the defence's case for them - and there is a history of EULAs extending beyond reasonable and legally-defensible means, in efforts to concentrate all benefit and leverage on the side of the publisher of that license. That does not make such terms legal, and an EULA is only binding to the extent that it conforms to a nation's established laws.

An EULA is not a law, itself. And sometimes it is nothing more than a software company's wet dream. If a publisher can produce the customer behaviour they want through suggestion and over-bearing claims of authority within their EULA, then sometimes that is what a software publisher goes for, despite it holding no legal merit, and despite an end-user not being bound in any way to such terms.

An example could be: If Microsoft put forth terms claiming that a Windows license owner had no right to modify their Windows software, then that would be illegitimate, and non-binding upon Windows license owners - as property rights protect a property owner's right to make decisions regarding their own property (but not necessarily to distribute the modified instance of their property, and not to use that modified property with other services offered by the license issuer, such as online gaming).

An example of property rights protecting license-holders' manipulation of their instance of the licensed item is films: This why there are fan edits of the original Star Wars trilogy that restore the films to their pre Special Edition versions, with those modifications publicized freely online, along with the names of the people doing it, and documentation of their processes to do it. LucasFilm / Disney would probably not endorse such projects, because they often end up being shared on torrent sites - but a person is fully protected in doing whatever they wish to their own property.

A software company might take many liberties towards software-license owners, and I personally suspect that Microsoft is behaving well beyond its legal rights with the liberties it is taking towards people's Windows 7 / 8 OSes, and also regarding Windows 10's invasiveness of a person's PC. But so long as people don't decide to form a class-action lawsuit, Microsoft might feel entitled to continue abusing their position.

Forcing a change of a person's OS, such as from Windows 7 to 10, could be taken as a violation of a person's personal property, which is the licensed instance of Windows installed on their PC. A person who owns a license for Windows 7 does not experience a change in their license terms just because MS decides to give Windows 10 licenses away for free (particularly through any means where Microsoft acts by liberty of advertising and installing Windows 10 on machines). If anything, they just gain an additional license.