See, my problem with this thought is this - When one learns to deal with their illness well and lead a fulfilling life, regardless of preexisting conditions, they stop seeing it as an illness. It's the case with many that have lived with cancer, amputees, diabetes, etc. Very frankly (and this isn't directed at anyone), I really do think that most people can try harder and do more.

I understand that on a literal level, mental illness isn't because people aren't trying hard enough to get better, or lead better lives,

Honestly though, at this point it's almost a theology debate based on core beliefs. I firmly believe in moving forward without ignoring one's issues, rather than focusing on the issue. It's evident we all focus on it differently.