A name is something that people take very seriously — and yes, that includes online pseudonyms. Names are a part of who you are. And as the internet becomes more and more popular, and as most people are anonymous on the internet, who you are can be defined by a username. Most people wouldn’t just sit passively if their name was mispronounced or misspelled. This is a misspelling, in a sense, and it should be taken seriously.
People abbreviate my username all the time. If you are starting to identify as your username then maybe you’re spending too much time online.