Is it selfish of me to not attend my family reunion?

So, me and my family often have this family reunion lunch one day before the lunar new year. Im a 25M who is studying in 3D animation. My hobbies include breeding rhino beetles and playing rpg games. My favourite sport is going on rope courses instead of your regular football or badminton. You could say Im the weirdest person in history.

Last year, I was unable to relate to any of my cousins and not even my younger sister. If I remember correctly, they would often play cards which I would find intimitating to learn how to play, its just NOT my thing. We are not kids anymore so Im unable to mix in like normal. Before you ask about my little sister, she would not seek me out to join them. And if I start the conversation, she would talk to me like she is mad all the time. The younger Gen Alpha cousins often look for me to play with them. Which is fine, if Im not the ONLY adult hanging out with them for the day. The other uncles and their wives, my parents included, would be playing mahjong or talking about matters that don't affect or interest me. All in all, I was "a guy who is just there" in last year's reunion.

As a result, I have decided not to engage with this get together if Im going to be surrounded by people and feel lonely. Yesterday night, I decided to come clean to my parents that I don't want to return to the reunion this year and told all reasons. But naturally, my parents keep saying that its selfish of me to not join the reunion just because I cannot relate to anybody in the extended family. And Im a little scared of what my parents will do if I don't show up. Am I selfish for not wanting to join the upcoming reunion and "following tradition?" Or is it better to prioritize myself so I won't feel lonely in a crowd of relatives Im now unable to communicate naturally with? Advice is appreciated.

UPDATE: After all these unbiased responses, I will attend this reunion and give stepping out of the comfort zone another shot. I will try to focus on the good more than the bad. Thanks everyone.