Why would that be selfish? It's not affecting anyone else if they don't participate. Participate all you want, but nobody is lesser for not doing things your way. It would only be selfish if they stopped you from participating or forced you to participate to further their own pleasure.I believe people who insist on doing mundane things their own way are selfish. If I were in Isreal I would be happy to celebrate the Rosh holiday and if I were in Saudi Arabia I wouldn't have any problem celebrating holy days there either.