NEW YORK, Nov 5 (Reuters) - Elon Musk spent nearly half a billion dollars on the US midterm elections, but the record expenditure yielded little for the world's richest man and leader of SpaceX SPCX.O and Tesla TSLA.O. (Corrects the number of Republicans in the House Musk backed in the second paragraph to 37 from 43) By Dawn Kopecki, Sheila Dang, Alexandra Ulmer and Virginia Furness NEW YORK, Nov 5 (Reuters) -.