One can have no idea about why the particular camera just sold was not used. Hopefully not because of illness or because of other unfortunate situations.
However, there was a time that Leicas were felt to be a good investment. Recall the "special editions" that were shamelessly pandered around the world? Many Leica camers of all kinds were sold at increasing prices, and were placed-unused and in the original packing and boxes- into a safe closet and thought of as a hedge against whatever economic problems might develop. Surely such cameras could ALWAYS be sold for a higher price. The market for Leica cameras in Japan was reputed to have inflated the value of the classic cameras in the M series, the associated lenses, and all manner of older Leica camera bodies and lenses which appeared to have a relatively limited number of iterations. Dealers bid up the value of such cameras until the "greater fool" was left with some specially colored Leica, with an exotic snake's skin on the body celebrating some King's birthday, was being sold for thousands of dollars.
The price that the current camera sold for appears to be a bit more than one might expect on EBay.
Best wishes to the buyer in the hopes that the camera will be used until the camera is burnished and scratched from taking thousands of photographs....just as long as there is film....and one must be happy to note that appearance of the new Silvermax and the continued presence of 35mm film.