The thought that discipline would eliminate the need for statins or GLP-1s is a nice fantasy. It appears that all it does is increase stress on the patient and make them feel like crap because they're blaming themselves for something out of their biological control.
When I had high cholesterol, I tried diet, which didn't touch it. I tried 9 statins, failed on all of them. Niacin didn't work. And now I stab myself every two weeks with Praluent, and it works beautifully. I'm looking forward to fewer heart attacks.
Diet and exercise didn't bring down my blood sugar numbers enough, and I've tried several drugs that didn't work for one reason or another, but now the GLP-1s seem to work where others didn't.
As far as I'm concerned, they're essential tools.