I was reading a book about Leonardo Da Vinci with my son as part of homeschooling him.  It ends up that nobody thought too much about he Mona Lisa until was stolen.  When they found out it was stolen, there was tons of news and when it was returned to the Louvre, it was suddenly super popular.  If it was never stolen, it may have never become the famous painting it now is.  It probably would've remained one of many nice paintings by Da Vinci.