To host your own infra, you dont need to build data centers, etc. Many just rent out physical space in datacenters.

Why the downvote? I know of multiple companies that went that route.

Google wasn't really a cloud provider for like 15 years and hosted their own infrastructure that entire time.

That's not exactly fair, the first decade+ of that pre-dates the public cloud.

The idea to use hosting is much older. Many companies offered services like that even in the 90s with AWS it really scaled up and the quality for hosting then improved across the globe.

Did they offer services like RDS, S3, SNS, SQS, Autoscaling, Route 53, load balancing... because those are what make AWS so valuable.

SQL and Domain Names was very common even in the 90s. The other concepts hadn't really evolved. Even AWS only had EC2 and S3 in the beginning. I'm just trying to relate and point out that Google decided to self host, rather then depend on someone else - which for a business that exponentialy grows is the best way, even today.