Based on personal experience and anecdote (i.e., reading queries from desperate computer users in help forums), it appears that Microsoft has embarked on a truly sleazy strategy regarding the operating system it sells you (which unfortunately controls the PC or laptop you bought from someone else). It's a practice of controlled obsolescence, where they leverage their own incompetence in the security field to get you to "upgrade" (that is, purchase) a more secure product.
As most people know, Windows integrated web browsing with the rest of the computer's functions (a bad faith response to an antitrust suit in the '90s -- long story), making it possible for third rate hackers to invade your PC through "exploits" on web pages. To patch these "exploits," Microsoft issues a steady stream of fixes through a process called "Windows Updates." Your computer pings the Microsoft website periodically to receive these.
In order to force users to switch to its newest operating system, Windows 10, Microsoft is deliberately slowing down, or even halting altogether, the updating process for earlier operating systems. I have Windows 7 on a PC (that I use for music) and a small laptop (for traveling). The PC requires close to an hour to check for, and download, updates, where it took only minutes a year ago. The laptop stalls out during the update process. Many other users are having these problems, judging from commentary and cries for help online.
You might think that each "upgrade" gives you a better and more sophisticated operating system and that's why you should keep switching. In fact, most are just tweaks on Windows XP, the last really good OS Microsoft developed (in the early 2000s!). Many users would be content to keep XP on their machines, or Windows 7, the company's second best OS, for years, until the hardware failed. With XP, Microsoft famously declared the "end of support" about two years ago. With Windows 7, they haven't declared an "end" but are making it more precarious to use, due to unpatched vulnerabilities, during a transition period where they are also offering a "free" version of Windows 10 (and even trying to sneak 10 onto your machine running 7).
Holding security fixes for ransom is a dishonest business practice that, if done by a local merchant in more innocent times, a customer might "report to the Better Business Bureau." Today, probably nothing short of a class action lawsuit would force Microsoft to be a good corporate citizen. But as individuals, we can make "consumer choices." So, here's the self-righteous testimonial (*smiles, holds PC up next to head for the camera*): I'm now using Linux Mint for most of my everyday computer needs, and keeping the Windows PC offline as much as possible in my music studio. When the laptop stops working or becomes janky with malware, I'll replace that with a laptop running Mint. It's minty fresh!!
Update: Apple led the paternalism curve and still excels at this. If you have a Mac desktop running Yosemite it will nag you to switch to El Capitan. Linux is the only "big three" OS that doesn't treat you like a thumbsucking infant.
Update 2, 2017: Microsoft offered some patches to speed up updates for W7 users. The catch is that the updates themselves are now offered only in monthly cumulative packages. This makes it easier for MS to slip in bad stuff that can't be removed by yanking single updates, as you could before. Since they don't seem to be forcing me to use W10 anymore, I've been installing the monthly crap and haven't been as vigilant as I was at the height of the "get 10" push.