There are ways to try to upgrade to Win 10 from RT but you will likely brick the device.
These devices were not cheap to purchase. Customers bought them in good faith, expecting Microsoft to support them for a good long while. Suggestions to throw the device away and purchase a new one... now that's really helpful isn't it? Not everyone can afford to do that, and they rightfully expect the system they invested in to last and be supported more than a few years.
I firmly believe it is Microsoft position that THEY own your device, and will do as they please with it weather you like it or not.
I had a Surface RT given to me... Thankfully, I didn't pay a dime for it. I will never purchase a Windows branded device. If the Surface RT, phones, and constant updates to Windows 10 (Like permanently mapping your F7 key to caret browsing) hasn't turned you towards Apple, Android and Linux, you must love throwing money down a hole.
Microsoft has a long history of ignoring it's customers, brushing them off, and using scripted technical support when their answers don't even apply to your needs. Microsoft decides what's good for you and the destiny of your devices, not you.
Like I said, they act as though they own the device and your just a noisy app that deserves no attention.
Microsoft and the cell phone industry should recognize that consumers would like to keep their device as long as possible instead of creating "forced obsolescence" every few years to sell new products to folks who don't actually need a new device. It's a money game, you and your device will never be respected to the degree of a dollar in their eyes.