For me the decision to start using Linux was a matter of (a) making optimal use of my older hardware, (b) not wanting to be stagnating in an old Windows version, and (c) wanting to use free software/open-source (FOSS) as much as possible. It was worth it to me to climb whatever learning curve I had to go through to save money which I would have otherwise had to work for to pay for everything I needed to stay on the latest version of Windows.
I get hand-me down laptops from friends, typically who use Windows and find the machines so sluggish after a few years they are ready to chuck them and buy a new computer. Saving these computers from landfill is one objective, but also my kids need computers for school and I want them using the most secure and speedy systems. How do I do this with computers that range from 5-10 years old, that originally shipped with Windows XP, Win Vista or maybe Win 7?
The answer is to install some Linux distro on these machines. It speeds up the system tremendously. I can be assured to be on the latest patched machine and I keep updating to catch any potential vulnerabilities. I have tons of FOSS that gives myself and my kids productivity tools, and it is preferable to using a ChromeBook where they need to constantly be online or use cloud-based apps for everything, and hand over their privacy to 3rd parties or get ads.
Could I put Windows 10 on these 5-10 year old machines? Yes probably. I recently upgraded all my office to Win10 using many of the original computers that are close to 10 years old. Clearly I need Win10 at my office because of proprietary software I need to run that is only available on Windows. Previously for a while I had Linux on the office computers with WinXPMode in a VM to run the software. It was time to update for security and other reasons, and I was pleasantly surprised that Win10 was fairly easy to install and the machines didn't take much of a performance hit. I was not going to try and run Win10 in a VM, then it would have been very sluggish.
But if Linux works faster with less resources needed on my home and kids laptops, and we can do everything we need to do, why not? But this is not a debate as to the superiority of one OS versus another. It is to point out how important it is that we DO HAVE a choice! Let us not take this for granted! In a world dominated by Microsoft and Apple, I say HURRAY to having a free 3rd party OS that has many iterations, customizations, versions, desktop environment options and huge library of software that gives people freedom to do their computer work any way they want!
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Not to mention whenever I install Win10 on a machine it nags me to buy a license or else I have to find some old Win7 or 8 key to register it and hope it is not being abused out in the wild (and Microsoft could pull the plug on the "free" upgrade path anytime, it was supposed to already be pulled). Most machines these days don't even have a sticker, they are OEM installed in the BIOS so good luck with that. Yes I can use Win10 with the water-mark but it is annoying otherwise ads galore, lack of customization or else fork over money.