Can people on the first floor swim? Books are the best swimming training class. Can people who can't swim teach themselves by reading? There are many people who can swim by themselves, but just look around and see if there are any books to learn. Is there anyone who swims better (basically ugly)? Don't talk nonsense if you don't understand!

The reason why swimming is difficult for self-study is that you can't see your own movements. The more you practice wrong movements, the more difficult it is to correct them.

So you still pay for a coach, usually in the swimming pool.