I’ve discovered why there seem to be no famous Belgians. It’s because you think they are French (Magritte, Simenon), Dutch (Dries van Noten, Kim Clijsters), British (Audrey Hepburn) or American … or something (Django Reinhardt).
I have also discovered that this, like so many of my other ideas, has already occurred to somebody else.
Perhaps the reason it happens is that very few of them stay in Belgium once famous.