After all, most companies using the "cloud" still have on-staff IT anyway, since non-technical people still cannot manage AWS or any other cloud provider on their own.
Cash flow is another thing - lay out big money for redundant on-site servers and supporting hardware today, or pay as you go and use the cloud. Even if the cloud is ultimately more expensive, it's easier for C-suite folks to plan for a small monthly expense vs. huge up front expenses and then dealing with failures and upgrades, etc.