That's because they're also counting all the server on a rack rental companies as cloud market share. If you look at just the cloud the way AWS does it - running code through their service in various datacenters as a service, it's above 50%.

Source: I work in Critical Incident Response/IT Remediation

AWS is absolutely a monopoly just like Microsoft has a monopoly on Corporate/Enterprise OS's tied to Domains. From a solely cloud based provider - not the Equipment renters or Volume based licensing.

AWS is a monster - Their market share is well over 33% regardless of how many articles you google to link me. I am balls deep buddy. It is well over 33% (At least in the US)