A lot of healthcare facilities are running EOL operating systems like Windows XP or Windows 7 because the programs they use for billing or other reasons are stuck on that version. You would be shocked at how prominent this is across most "modern" infrastructure. The resistance to change stems from a "if it isn't broken, don't fix it" mentality. Pagers are still the most reliable ways to reach a doctor, which is why they're still used, not because they're necessarily the most secure.
As easy as it is to point blame at "duh boomers" the situation with healthcare in particular is much more nuanced. Though I do agree that any luddites in charge of major hospitals are not helping the situation at all.
IIRC this is how those Elon musk crypto livestream hacks worked on YouTube back in the day, I think the bad actors got a hold of cached session tokens and gave themselves access to whatever account they were targeting. Linus Tech Tips had a good bit in a WAN show episode