There’s a weird divide between self-determined identity and external classifications. Often, a culture forms around the label and the external label stops being relevant because the term has more social/cultural implications than practical implications. Some people internalize the label as that’s how they wish to steer their future interactions, and others ignore the label and move on with their lives.
You can watch all of Star Trek, and some parts of society will label you a Trekkie if they find out, but it’s up to you whether you choose to identify as a Trekkie, or just go about your life not making a big deal about it.
To accept it, you just move on with your life. Find the next thing you should do and do it. The more you dwell, the harder it will be to stop dwelling, so just break the cycle and go do anything else.
You will encounter plenty more people who are insistently wrong. Each one will affect you less than the last.