How/why does a writer chose their special nom de plume? That is a question

I pondered on when I discovered today that the real name of Alberto Moravia,
the Italian novelist and writer, was actually PINCHERLE.
snip>>>>>>>>>

You may add to the puzzle the Italian Jewish writer Italo Svevo >from Trieste.
His real name was Schmidt. Trieste, part of Austria, seems
to have been an entry point into Italy for Ashkenazi
Jews.
Jules Levin