It is more in Microsoft's interest to get everyone up to Windows 10, not ours.
The more people who move to Windows 10 the less people who run older releases of Windows and the less time they have to spend fixing the older releases.
The "problem" with Windows is that once you have bought it Microsoft get no more money (for example those who bought Windows XP and are still on it have spent no more money with Microsoft).
So Microsoft want to move to a subscription service with Windows, rather like they have with Office 365 (which you have to pay for each year to continue using it).
So once we have all been battered to move to Windows 10 Microsoft will probably announce that from now on you have to pay £30 a year (or some figure) to carry on using it. That way they get a regular revenue stream.
I am registered as a Microsoft Partner (people who work WITH Microsoft to sell their products) and I have already had emails from them encouraging me to get all my "customers" to Windows 10 so they can introduce the subscription system.
Those of us who stay on Windows 7 will never have to join this subscription system so can carry on using Windows 7 for free as long as we want to, unlike those that move to Windows 10.
Article here about subscription for windows 10.
http://www.v3.co.uk/v3-uk/opinion/2420062/microsoft-could-be-taking-us-to-a-subscription-based-future-with-windows-10