Uber hosts its own infrastructure, so does Google, so does Facebook. All three of those companies have no problems remaining focused on their business models without turning into a "datacenter company."

I strongly dislike the notion that on-prem hosting is somehow a bad thing, or too cumbersome, or otherwise totally solved by cloud providers. AWS specifically is hugely convenient in a number of ways, but it doesn't come close to the cost savings from running your own infrastructure. You need a pretty large amount of capital and engineering talent, but it really is worth it even in the short term (~3-5 years).

I think people would be shocked at what the money comes out to be if they saw costs from companies doing their own physical infrastructure. AWS makes you pay through the nose, seeing the difference would change a lot of minds I'm sure.