Conference Spam

What is up with all the conference spam? I think I get more of that now than predatory OA journal spam. Hitting the delete key is not that big a deal, but recently I spent a day with no email access and it struck me just much conference spam I get in a single day.

Does this actually work? Do people actually attend expensive random conferences in far away locations? I find I have more than enough conference travel attending well known meetings and/or workshops run by reputable societies or funding agencies. Certainly more than I can pay for with grants. Who attends these meetings? Someone must, or they wouldn't have proliferated so much...