It's a bit off-topic, but in a way being a Buddhist monk is a very selfish lifestyle. You don't have to take care of yourself, society will take care of you. You don't contribute much to society apart from perhaps some religious services. In my opinion it's not a good way of life.
"Monks" are not one, monolithic community, so it's hard to argue one way or another whether they contribute anything meaningful back to a community. Here in Japan, many Buddhist orders are downright wealthy (from donations), and use their considerable resources to preserve traditions and history. I doubt that you can put a dollar value on the benefits of keeping cultural history alive. In a sense, it's not too much different from the function of the Metropolitan Museum in New York. Of course, Buddhism is a many-facted religion that manifests differently in different places.
I've always understood the relationship between societies and monks (priests, ministers, nuns, etc.) to be one of "offset". Monks are taken care of so they can pursue the esoteric studies that the common person has no time for. In exchange, the common person's spiritual/religious/etc. enrichment is guided with assistance from the monk, similar to how patronage happens in the arts.
I'm sure this could be explained in an even more conduct way, but I'm having a hard time putting down in words how I see the relationship works in my mind.
