I think for most levels of safety you would target, a pure cloud solution is going to be cheaper. E.g. if you decide you need a backup that's independent of your primary cloud provider and any staff with access to that, you can probably accomplish that more cheaply with a second cloud provider than by self-hosting.
For plenty of use cases I actually agree with that conclusion. With the caveat that I would add: accompanied by a suitable non-cloud back-up of critical data, code and configuration data held on a medium that is not accessible by the same people that administer the cloud stuff.