Neither is Saint Patrick...
Saint Patrick's birth name is Maewyn; born in Britain. I think the story goes, he was kidnapped into slavery and brought to Ireland. He later escaped to a monastery in France where he then converted over to Christianity. He did go back to Ireland as a missionary and made Christianity more widespread. He later became a Bishop, and then after his death, he was named Ireland's patron saint. Thus leading to all of the celebrations...in Ireland, as well as the U. S. and other countries.
Saint Patrick's color wasn't green; but blue. The use of green began during the Irish rebellion when the clover became the symbol of nationalism.
Why So Many People Celebrate This Day?
I don't know. It's not a legal holiday anywhere here in the United States. The only thing I can guess is that there are many Irish descendants around the world...and it's definitely widely celebrated by them, because this is a way of celebrating their heritage.
And did you know that St. Patrick's Day isn't about drinking? ...
So much to learn. I bet there are so many people out there that don't even know why they are celebrating St. Patrick's Day.
However, if you are one of them, be safe.