Well, "years" might be a little bit of exaggeration. I mean, there always is something more to learn even after 10 years of experience, but it shouldn't sound as terrifying as you make it sound. To be somewhat good you need only few basic skills (which that book doesn't teach you, as I already said in another post, but there are other books and courses anyway), not very long period of pretty intense practice and yes, here your life-long journey begins, but you already can be quite confident about your drawings.

It's like, you know, that sushi-making stuff in Japan (as well as many other things): it's considered very difficult and you need many years to learn how to make sushi and there are some 86 years old master that'll tell you how he even now dreams about sushi and improves his skills and whatever. Yet you can take 3-hours long lesson somewhere in Europe or USA and start making pretty decent sushi for yourself.

Or programming, or everything else. Anyway, making some real work of art is more about your personal qualities like imagination than about "life-long learning". But there's always something more to learn nevertheless.