Every product follows demand curves. At a price of 0 you could find infinite usage. This has nearly zero relation to how much it costs to provide the product.
Infinite demand isn't a thing. Even if they'd offer free compute forever (not likely possible) I and many others would still use local models that we have full control over and that do not harvest our personal data.
Maybe I'd be willing to pay $10 for product A if I had other options. But if there's a product B for $3 that's not quite as nice but still ticks all my boxes, then product instantly becomes a lot less attractive.