You don't need enough IPs to go around; you can always assign a private IP address and do NAT (this is how most VPNs work anyway). But yeah, I don't understand

You don't need enough IPs to go around; you can always assign a private IP address and do NAT (this is how most VPNs work anyway). But yeah, I don't understand how they're paying for it. My best guess would be they found a loophole to exploit peering agreements, similar to how small rural telephone companies will set up free conference bridges because the big telcos have to pay them connection fees. Or they're just capturing info and selling it (unlikely; personal information just isn't worth that much and it's easy enough to buy already from data brokers). Or they're MITMing the big ad networks and showing their own ads instead. I consider this the most likely scenario.