Basically, a few years ago I thought it was easier to build my own framework in Golang, C, C++. I've also used PHP, Node and Flask from time to time. After doing all that, I had a pretty good understanding in how it all works, and can see the beauty in some of the way Rails works. I definitely think it'll keep growing and is worth learning if you're into web development.
citing the parent
no that's bullshit, just do the rails tutorial online and you'll be good to go. OF course you need to know Ruby. Like with any other language, you can't just learn the framework.
If a person know Git, HTML, JavaScript, and one server-side language, I can teach them enough Rails to build production apps in a few weeks. I've had a lot of success with that.