I see it as a community. We write and share our papers as part of our jobs, we review each others' papers as part of our jobs, we help to run the conference as part of our jobs. Everyone contributes to run the system.
Nobody buys articles for $35 a piece. All major universities and companies subscribe to the ACM or whatever your field's organisation is for you. And guess who runs the ACM and other organisations? The community does! People from the community serve as leadership and help run things.
Yes the ACM gets some money to run their website, conferences and outreach programs. I don't think that's crazy.