I do get it. For many it's a form of personal catharsis, but it's also a brutal reality that research dollars and public funding for resources depend a great deal on how much of a personal face can be put on diseases. Think about how many diseases out there are competing for your donation dollar and what makes you decide to donate or buy merchandise supporting one over another.
People don't respond to numbers. They respond to emotional appeals. Cancer in general and breast cancer in particular is a huge money magnet and few people ever question whether that money could be better spent on research into other diseases.
Fair enough. I'd guess the reasons are many and varied - when I say "don't get" it's more a reflection on my personal reaction. But I'm not from the US, and although research and funding is an issue here, medicine is seen as social necessity rather than a matter purely of $. The US attitude is different, simply because you don't have the social medicine mindset which is the backdrop elsewhere.
The part I DO understand is the initial I-will-not-let-this-stop-me. But sadly its a false hope - somehow, even if only for awhile, it will change your life dramatically. It's like anything human, I guess, and the range of reactions will be just as wide.
Incidentally, another reason the munchies/hypos/general fussers are such a pain in the arse on some medical communities is that doctors use them. If an illness is a rarity, even a specialist may see only a couple of cases and never see a non-"textbook" case so specialists get info from the forum. Yet another way these people can do horrendous damage because their fabrication may actually skew opinion. This is offset by their not claiming rarer illnesses through lack of knowledge, but the internet has blown open a massive amount of hitherto unknowns to these people. Rather like the very small number of genuine ME/fibro cases, the last thing you want is them glomming onto your thing because it really harms those with the real thing.