Who came up with the idea of celebrating “international days”?

And what does that exactly mean?

I just learned the day before yesterday was the “International Day of Older Persons”.

Are we celebrating that we have elderly people around us? Why? How? I mean, just that day?

The United Nations is one of those institution that does not make sense any more, another cog in the propaganda machinery. An institution that is funded with tax money from citizens from all around the world.