My father-in-law was a very bright professional man. Raised during the Depression, moved west as a youngster to CA during the Dust Bowl migration, this guy had seen more than his share of scammers and was nobody's fool. That said, I posted his story over a year ago on a thread about scam calls, but am repeating it now as a reminder:
I get calls about nonexistent car warranties, student loans, accounts in collection, mystery nephews in foreign jails, and so forth. I don't answer unfamiliar numbers and delete the messages, but don't bother blocking their numbers because they're nearly always spoofed.
Obviously they catch enough fish in these nets to make it worth their while. Case in point:
About five years ago a Jamaican ring started fleecing my widowed father-in-law with a "you've won millions, but it's going to cost a bit to get the money released" story. My MIL had died a few years earlier, had always been sharp as a tack, and would surely have figured it out immediately, but FIL was trusting, affable and had apparently become easy prey in his declining years.
They got at least $10,000 in cash from him before a daytime caregiver became suspicious of the increasing number of incoming phone calls. He listened in on an extension, realized what was happening, told my FIL to hang up NOW, then called my husband. Between the three of us, my FIL, the bank and the police, we patched together what was happening.
We immediately forwarded my FIL's phone calls to my office number and I changed my voicemail to non-identifying "leave a message." These creeps called relentlessly - all hours of the day and night. They became threatening and frustrated that I wouldn't let them talk to my FIL and were furious with me. Their clumsy tactics and lack of sophistication would have been laughable if it weren't apparent that they were more sophisticated than my dear, sweet FIL had become.
Clearly their prey were the trusting, the confused, and folks with diminished cognitive capacity. Truly slimy.
Desperate to keep the money flowing, a couple of their operatives brazenly showed up at my FIL's house with the story that they were delivering (an unordered) pizza and needed to take my FIL to the bank. My FIL's caregiver - a quite large man - wouldn't let them in or my FIL to the door, and threatened to call 911 if they didn't leave immediately.
At that point we knew my FIL could no longer safely live alone or remain in that house. FIL was terrified by the pizza incident, embarrassed that he'd been scammed, and agreed. He chose a beautiful nearby assisted living facility where he thrived, found a girlfriend

, asked my husband to manage his financial life, and was never again bothered by those creeps.
On an aside: A bit into this, a NY postal inspector investigating this fraud ring caught an envelope my FIL had sent to a known scammer address. My FIL's phone number was publicly listed so he called and left a message, which went to my office phone. Of course I checked this guy out ten ways from Sunday before talking to him.
The investigator was very illuminating, explaining the nature of the scams, how they first hook people in, slowly suck them dry, then get these now-desperate folks to do some of the ring's monetary collecting and forwarding work for them. Among the victims he'd talked to were doctors, lawyers and psychiatrists.
The unopened envelope containing several hundred dollars in cash was returned to us and required my picture ID to get it released.
A couple of years later they tracked him to us and an unordered pizza came to our house in my FIL's name. The Domino's delivery guy - obviously not part of the scheme - said the order had been called in but no payment made (so no CC info to track). We tipped him (this wasn't his fault), briefly explained the situation and declined the pizza. When we called the police the officer said the Jamaicans probably had someone parked nearby, watching to see if we'd accept the pizza or if my FIL appeared.
Our family was incredibly fortunate. Many are scammed out of everything.
DH & I have talked to our children about not being shy when/if they see our faculties slipping. At that point, we'll appoint one or more to oversee our financials.
p.s. LAPD's classification for this kind of crime is "defrauded by trickery."