The devs just did their jobs. They want to keep players subscribing until the next expansion and the result for the fishing-lover players is this unbelievable RNG. They do not want you to be fun, they want you to suffer. The legendary fish things have always been like this. Opabinia, the Ruby Dragon, Lancetfish, all of them took me more than 8 months (in case of the Ruby Dragon it took me over a year). It clearly shows that the devs do not care how long it takes for you. They want to torture you and if you still keep subscribing, they made their jobs done.