I've never been sorry that I rescued a betta, whether it lived or was terminal. There's pics of a really severe case of neglect on my page (Maggie). She had terrible rot & was in filthy water with high ammonia. Labeled as a "male VT", she was clearly a female. She never rally colored up & her tail was more than half way gone & all other fins pretty much gone. I did everything I could to save her & she responded to treatment for a couple weeks before it came back really bad despite the best of care & medicine. I had to put her down after she gave up fighting. It was hard, but I don't regret it one bit. I may have a new King rescue coming my way when I get home from house sitting next week & I currently am helping a really tiny baby survive. Good luck!