The same reason people watch shows like "Real Housewives of..." or any of those other contrived "reality" shows, you watch for the train wreck appeal. I love watching tanked, not for the goofy or obviously faked "disasters" that occur, not for their tank building expertise, but for all the dumb stuff they do that isn't pre-written slapstick. I just have a hoot when they pick fish out "Oh this tank is a volcano theme, so we'll choose some flame angelfish because fire is related to volcanoes, and then we pick some blue devil damsel fish because hot magma, hell, devil, yup all related!"