The upside is that most cheap phones are only in service for a year or two at best. Unpatched flaws get thrown away with the phone.
This kind of thing is uninteresting at this point. Flaws are found, patches are issued and the sun rises every morning. I'd like to see good statistics (which are likely impossible to collect) about the amount of real world harm caused by most of them.
Far more damaging is people's own idiotic behavior. We have know about HIV floating around for decades yet people still have unprotected sex with relative strangers all the time. You reap what you sow.