That's one way they make money. That's the reason sqlite exists.
By the time TH3 was added in 2008, SQLite had gained a fair bit of traction across multiple industries. Though I totally agree that the comprehensive coverage is a leading reason why they've been so stable over the last ~20 years.
So indirectly, TH3 is why they (continue to) exist and (are able to) make money, but it isn't a direct line as one might assume.