I think people celebrate to honor those wh0 are being celebrated.Just like we celebrate presidents day,it’s a special holiday where 90% of the people in the world celebrate the presidents that have died or been killed recently.But some  people don’t celebrate presidents day.Some people might just sit and if they have a presidents day parade they might watch it.Some people on the other hand might be in the parade or have a special  party to celebrate our presidents,witch if some of are presidents were still alive i bet they would love to see all the wonderful things some people are doing for them.like parties parades and other nice things.Also people celebrate to show honor respect and last but not least love.thats why so many people celebrate these holidays or special because they love thier state or country,it dosen’t have to be a big thing it still counts as celebrating something.