There is no meaningful security difference between commercial operating systems and hypervisors when considering technically competent, commercially-motivated attackers. No systems built on such insecure systems can stop even minor attacks staffed by a single-digit number of FTEs. Maybe there is a material difference, but it is irrelevant compared to their total inadequacy relative to the present threat landscape. The person who can climb Mount Everest is still no closer to achieving orbit than the person who can only climb a tree.

To move beyond the mere practical aspects, even theoretically you are wrong. The techniques needed to develop a secure hypervisor are basically exactly the same techniques needed to develop a secure operating system. They are almost trivially transferrable. If you can do one, you can do the other. So, again, no advantage to preferring a hypervisor based solution.