Until they get borrowed or even "borrowed". Every other day in my office has a mac user wandering around looking for some sort of video adapter dongle or similar, asking if anyone knows who borrowed theirs. Person A isn't in the office, so person B borrows their adaptor 'just for now' and then absent-mindedly takes it home, leaving person A scratching their head the next day.

The problem with dongles is more than just price-point.