He kind of touches on this in point IV, but never mentioned specifically: the cost comparison is not AWS vs ovh. It's fragment-of-EC2 vs ovh. If you need a predefined small number of VMs and no other functionality, it would be silly to go with AWS. But on the other hand, if you want a set of servers of a given class spawning on demand, with traffic coming in via load balancers, with integrated certificate and DNS man…
I also think the "pay someone to set this up" factor is underestimated. Person time cost eclipsed computer time cost a long time ago. If you've got the market demand to need that kind of infrastructure, you're almost certainly operating at a scale where you can afford to dish out the extra dough because it will reduce downtime and overhead enough to make the ROI worth it.
I'm not an expert in this (I'm just a code monkey who works with scientists, and side hustles as a small time sysadmin), but reading books like "Release It!" and reading blogs (especially DevOps, as I'm looking at getting into that) gives me the impression that if someone could reduce their costs while still getting the value AWS gives, they'd be doing it. I mean, maybe it's a well-kept secret (especially if it gives a market advantage), but if it's so easy, I'd think everyone would be doing it, and AWS would be out of business.
Edit: I concede that startups probably don't need AWS; what I'm thinking of above is big, old, established companies that believe "no one was ever fired for buying AWS." But I do believe that you have to have smart, motivated people in order to grow while staying lean, and just because we hear the survivor stories of startups that do, doesn't mean there aren't dozens that die because inexperienced devs though they could do better than AWS, and were proven wrong.