The particular problem I have with your reply is it is half wrong.
Textbooks tend to be filled with crap themselves. I have a feeling you're judging the contents of 'educational' textbooks rather than the corpus of all textbooks.
Next, you are not an island. You need both things, insight from other people that are learned in said thing your attempting and practice. If you practice without the insight you're going to waste most of your life accomplishing something you could have learned from someone else in a few minutes.
Textbooks tend to be filled with crap themselves. I have a feeling you're judging the contents of 'educational' textbooks rather than the corpus of all textbooks.
Next, you are not an island. You need both things, insight from other people that are learned in said thing your attempting and practice. If you practice without the insight you're going to waste most of your life accomplishing something you could have learned from someone else in a few minutes.