I'd rather just never lose a fish to preventable diseases. I have so far managed to dodge bullets, but now new fishes are coming from QT vendors and I am taking biosecurity seriously, including frags and snail shells. With the resources we hobbyists have these days to deal with disease (such as peroxide and pre-QT fish) I just don't understand the mindset of knowing about these diseases and playing Russian roulette any time I want to add something to the tank. It's not hard to HTTM new arrivals and fish from QT vendors are not expensive enough compared to mystery fish to justify taking the risk to me. I would be absolutely livid if I lost my clownfish (the first SW fish I got, 10 years ago) to velvet or brook despite knowing how to prevent them from entering my tanks at all.