It isn't a free product. It's a paid product with a free "introduction tier" that helps them capture the open-source ecosystem, so that when your company needs paid services, they are the obvious choice because everyone is using it already.

Basically the same deal as "educational licenses" for expensive software suites. It isn't a freebie at all; it's an investment into future customer acquisition through lock-in. That's how you're paying for it.