Having worked in several industries before landing in software development, I can tell you that the most common form of hubris we have as an industry is in thinking that our domain is where the hardest problems live. Or in thinking that the level of difficulty of our challenges has a 1:1 correlation with those of the business.
Building data centers is hard because there are not a lot of places that you can build them effectively. Large scale, specialty real estate deals are the kind of thing that effect a company's financials in a big way and for a long time -- much longer than the market cycles where you determine whether or not to continue or abandon your hypothetical, nascent cloud offering service -- and are exactly the type of thing that market investors will pillory your company for if you fuck up.
If you're Amazon and you're starting off in the datacenter game and it doesn't go well, you can always transition the property into a distribution center. Those are useful to you anyway.
If you're Facebook, what are you going to do? Who are you going to sell this $800-1200/sq ft (that is the cost of building a turnkey DC and puts AMZN's largest datacenter somewhere between 172-258mil and that's just one of them) "big box" to? They should make a multi-billion dollar investment for that and hire a global enterprise sales organization on top of that to sell it?
Maybe it's not so much that what CIOs say is divorced from reality but that they see reality at a scale that you don't. Their abstractions may not make sense to you.