I think the point of the quote would be to create a sense of gratitude along with a good dose of reality in those sleeping peacefully only because of those rough men. As a side note, some of those 'rough men' are the most soft-hearted, loving, generous people on this planet. I have had the great fortune to be the wife of one, a sister to one, a sister in law to another, as well as being blessed enough to count a few of them among my friends.