Believe me, because of the nature of my day job, I know what you are talking about.
Unfortunately, software operating systems never have been and never will be designed for human nature and all the warnings, antivirus updates, and admonitions (received with eyes glazing over, lol) are not going to change that fact. Their usability depends on their accessibility but it is also their achilles heel. Most folks do not have the same mind set as those that are designing the software programs those same people want to use, so it will always be an uphill battle to ensure cyber security. The result is a big pay day for the hackers and cyber security warriors, alike. Furthermore, the reasons why most folks stick with the older operating systems is because they just happen to be stable and work for the programs they are using on a daily basis. Some programs will not work on the latest and greatest OS, but folks are loyal to those things that do just work so they stick with the older configuration. Profit drives OS companies to move on to the next OS iteration and the need to support the old OS is just a risk and resource drain, but none of that matters to the person left behind because they have been using the same program for the last 10 years that "just works" for them. Just a fact of life...