why is Mona Lisa being preserved and displayed in France when the artist who made it was Italian?

The artist was Italian. The artwork belongs to France.

Imagine a world in which you can't take your belongings home with you...

Thats a good question 🤔

I suspect ownership has something to do with it.

Leonardo gave it to the king of France while living there during his last times.

If you don't take art from other places and take it to france, they would not have a good display of art

Because the Louvre won the auction bid when it went up for sale.