Like all IT debates, this one is silly.
The Cloud is growing rapidly, and the server market continues to decline - as fast as the PC one really. These are the facts (as reported by numerous analysts and the Register)
All companies that have bashed Public Cloud before have launched their offerings since.
In a few years it will all be over. Like it was for mainframes and numerous other technologies since.
ROI on the cloud is clear, and it is far cheaper than build - the reason for discrepancy is that no IT person counts it properly - they always leave out massive chunks (most frequently themselves), but also space, redeployment, power costs, you name it.
Ultimately, the reason why all companies, not just SMB, but large ones, public sector choose AWS, is very simple: got to market and as a vendor to quote for 1) build your own (you manage) 2) colo, and build - they manage, or 3) private cloud - then compare to AWS. Having helped companies (as independent client representative) to make the choice, it was always AWS...
Final point. For vast vast majority of businesses, NSA / GCHQ is completely irrelevant. Unsurprisingly, most companies globally do simple things - build houses, make chairs, cars and vacuum cleaners. Sell travel, or insurance, or feed people. The dont have trade secrets beyond their budgets and forecasts, and dont care if spooks see them. Public Sector too. Does it really matter that NSA has a list of school kids in Fyfe? Really matter? Worth paying 10 times over what your "local DYI" ICT provider charges you?