Like, relays are just websites. It's the same idea.
Most people don't make people pay to use websites. You can go to a website for free and they work just fine
Discussion
Those websites cost money, and those bills are paid through ads or product sales. The websites aren't "free". If anything is "free" *you* are the product. Same with relays. The hardware and bandwidth and time to maintain cost a lot of money for large-scale enterprises. Nostr is no different.