All Windows OS versions (including 10) eventually go the way of the dinosaur as do other OSes (Linux in all its distros is under constant development and older versions eventually get dropped from support). If you want to know the actual dates for the end of mainstream and extended support for the various iterations of Windows since XP see the Windows Lifecycle Fact Sheet. Windows 7 regular support has already ceased and extended support will end in 2020.
Windows 10 is not garbage. As far as I'm concerned it's a vast improvement over Windows 8, and brings back a number of features from Windows 7 and earlier (the biggest one being the Start Menu - though now in tile form) that make it far more comfortable for long-term Windows users to adjust to. Don't get me wrong, it is an adjustment, but I went straight from Windows 7 to Windows 10 and feel far more comfortable with it than I do with my partner's Windows 8.1 laptop.
Windows 10 is not "full of spyware" nor does it auto-install (at least not yet - and not ever if you configure your Windows update not to get recommended updates automatically). At the moment the Get Windows 10 (X) - AKA GWX - nag does install on Windows 7 (and Windows 8) and the files necessary to upgrade to Windows 10 do download, but you must trigger the upgrade process and consent to several different things before Windows 10 will actually install.
Windows 10 does include the Cortana Service, a direct competitor to Apple's Siri, and if you use it then it must have access to things like your contacts, e-mail, and other personal information to do its job. You do (or did, I never know if something's changed since the last install I've done) get a choice as to whether to activate Cortana or not as part of the upgrade via GWX or, I think, the ISOs you can download from the Media Creation Tool. You can simply turn the Cortana Service off if you so desire and the "Get To Know Me" setting under Speech, Inking, & Typing settings and then, if you're not using any of the other Microsoft Services covered in the Microsoft Services Agreement, you have pretty much the same situation you had under Windows 7 or Windows 8 as far as system telemetry back to Microsoft about how the OS itself is operating and its interactions with programs and peripherals.
If you elect to create a local account on your Windows 10 machine rather than one associated with an existing (or new, you can create one) Microsoft Account you're really working in an environment pretty much like Win7 or Win8 with regard to everything except system health telemetry.
There are a number of very good free antivirus products for home users. Take a look at Panda Cloud antivirus and AVG for starters. Also, Microsoft's own Microsoft Security Essentials (for Win7) or Windows Defender (Windows 8 and 10) work well, too.