How about laziness? Isn’t that the main factor for losing interest in learning Torah? The natural enjoyment of learning only comes after accomplishment of learning, not before.
And, unfortunately there are many learners out there who do in fact speak Loshon Hara. Learning Torah alone doesn’t seem to be a natural shield from speaking loshon hara. One must make a conscience effort to refrain from speaking loshon hara; learner and non learner alike.