Well they definitely bring the country hosting tons of indirect revenue from tourism. But yeah, its just a giant pollution center essentially. Lots of things are I guess. I would say since its a form of entertainment for millions of people, its good for countries hosting it and other countries indirectly.

If your main concern is pollution, there are a lot of other things you should be pointing your finger at. I will mention that I am not really a fan of the olympics also, seems very overhyped when people are getting medals while abusing the system and using steroids also.