Do you study poker? If so, then do you prefer books over online courses?

I've tried online courses and read books as well, and for me, books are much more efficient when it comes to real knowledge.

How do you feel about it?
Are you a profitable poker player?
(Stakes?)

Thanks for all those who answer my questions. I'm very curious. 😊

Books gave me fundamental knowledge, but online courses, open trainings and free poker inputs gave me technical knowledge.