Fitness is also a huge industry, as is physical therapy, as is the use of therapy for depression. If the medical industry seriously believed that exercise is a marketable treatment for depression, there are known and quite obvious pathways to monetizing it. It's far more likely that they either don't trust these studies, or that they don't think you can convince a large enough group of depressed patients to exercise.

The idea that doctors are not talking about exercise as if it's some big conspiracy to make more money from the top is ridiculous. Any doctor will say that exercise is the best thing you can do for yourself but most people also know that it's super inconvenient and most people don't follow that advice.

If anything, the people making it out to be some big conspiracy against mainstream medicine are doing it more for the money because they're often peddling some alternative medicine or supplements.

It's also because exercise requires exertion, which is effortful, and most people who need the exercise would rather spend money to not have to exert.

Does it pain me to say it? Nah, I'm numb :-/

Well you're lying because working out is like the top recommended cure for depression. My doc begged me to stop taking meds and run again because it worked much better