Security (we're a bank)
How is the cloud less secure than your on-prem servers? I would argue that it's easier to keep track of all the threats with the tools available from big cloud providers.
Now imagine you're aware that Amazon's retail arm is quite happy to launch competing products based on sales data from marketplace sellers, so it's not like they have strict firewalls protecting competitors who pay Amazon for services.
Now imagine Amazon offers you a bunch of security options that sound suspiciously like snake-oil. Like an encrypted storage service where they store the encryption key and transparently decrypt files when you request them.
Now imagine you know people with hypervisor access can do what they like to your VM and leave no evidence whatsoever. And your on-prem experience is that there will definitely be some people with hypervisor access.
Now imagine you've been through various audit and certification processes yourself, and you don't find yourself reassured by the knowledge Amazon has too.
Now imagine if you were a boss at AWS and you found an insider had violated policies and accessed things they shouldn't have. Would it be better for your career to publicise that widely, or reprimand the guy then hush things up?
Now imagine you've been an ambitious cowboy at certain times in your career, and although you've never accessed a competitor's data to give an edge to something you were working on, you can see how it would be a temptation.
I can understand how a person who believed all that would believe putting their business in their competitors hands would be a naive decision.