This is where I see things too. When you start out, all your value comes from working on your core problem.
eg: You'd be crazy to start a CRM software business by building your own physical datacenter. It makes sense to use a PaaS that abstracts as much away as possible for you so you can focus on the actual thing that generates value.
As you grow, the high abstraction PaaS gets increasingly expensive, and at some point bubbles up to where it's the most valuable thing to work on. This typically means moving down a layer or two. Then you go back to improving your actual software.
You go through this a bunch of times, and over time grow teams dedicated to this work. Given enough time and continuous growth, it should eventually make sense to run your own data centers, or even build your own silicon, but of course very few companies get to that level. Instead most settle somewhere in the vast spectrum of the middle, with a mix of different services/components all done at different levels of abstraction.
The DC will handle physical service for you if something breaks, you just pay for parts and labor.
All of this requires knowledge, of course, but it’s hardly an impossible task. Go look at what the more serious folk in r/homelab (or r/datacenter) are up to; it’ll surprise you.