It's not that uncommon. You have people making crazy threats (which they probably don't intend to carry out, but it only takes one..) all the time, and the police won't do anything but take a report because frankly, that's all they can do. So you end up at a certain scale having to investigate some of these things yourself.. by hiring probably somewhat sketchy ex-military types.
Yeah, having a threat intelligence and investigations team is very common for big companies.
If nothing else, it's probably safe to assume that someone like Mark Zuckerberg or Larry Page regularly get emails or other messages saying things like "im gunna go to ur house nd kill ur dog and ur hot wife"
Law enforcement doesn't have the resources to investigate every one of these, absent a credible threat of it actually happening, so corporate security / executive protection exists to, well, investigate.
I"ve seen Mark's security when he's out and about on campus. They're reasonably discrete about their jobs, given that on any given (pre-Covid) day there were probably hundreds of business and personal visitors on campus.
Personal security for CEOs (never mind billionaire CEOs) is hardly anything new. If I were Mark, received the amount of hate/threat messages he does, and had a young daughter, I'd do everything short of hiring the 82nd Airborne to follow me around.
Taylor Swift once said "I don't have security to look cool. I have security because people want to take me home and chain me to a pipe in their basement."
She wouldn't last five minutes chained in my basement because she'd start singing and I'd throw her out! Next if be looking for the person who put her there because that is not an acceptable practical joke! I'm glad she has security.
Retired police officers & feds of various flavors aren't uncommon in California. Their retired LE status lets them carry concealed without issue, even in downtown San Francisco.
For some positions, the ability to carry concealed was mandatory (e.g. the CEO's driver/bodyguard). Related aside: the CEO I'm thinking of wasn't allowed to drive himself in order to avoid any stock hits if they whapped into a kid running into the street after a ball (or what have you).
