I think that goldfish, since they are usually so cheap in the stores, are often just considered a "throwaway pet" that people buy on a whim, and don't really worry about whether it lives a long time or not.
I remember, back in the 50's, when I was growing up; they had little goldfish in bowls at all the carnivals when they would come to town. Of all the toys you could win at the midway, I always like the little goldfish the very best ! They were always so pretty swimming around in their little bowl. I am sure that my mom spent more money throwing dimes at the goldfish bowls, trying to win me one of them, than she would have spent just going to the Dime Store and buying one for me.
Then, of course, we had to buy a goldfish bowl, as well as sand, fish food, and a cute little castle for my new goldfish to hide away in when he felt like it.
I don't remember how long I had my goldfish, but I do remember that I enjoyed watching him swim around in his tank, and coming up to grab the food when I was feeding him.