My folks are getting up there in age, but they're still both as sharp as tacks. In the past few years they've had contractors, salesmen and service providers, and phone scammers all try to take advantage of them only to get absolutely shut down almost immediately. My parents take absolutely no bullshit and passed that lesson down to me. About four years ago they moved to be closer to me and my wife/stepdaughter, but the house they purchased turned out to be a bit of a money pit. They took it in stride and DIY'd as much as they could before calling in contractors to finish the rest.
A few months ago my mom calls me and says that a guy who did some subcontracting during renovations knocked on the door and flat out ask her for money. Not an odd job, not a recommendation, just straight cash. My mom realizes something's up and tells him that she can put his business card up at church and recommend him to people who might be looking for a contractor. He got really upset and swore at my mom to the point where the workmen putting in the new bathroom had to come escort him off the property.
"Well," I said, "maybe he thought he could take advantage of you because you're older. I'd make sure you guys set the alarm when you're home alone, just in case."
"Oh, we don't have an alarm. We never got the old one switched over after we moved in. We're far enough in the country that no one ever really bothers us."
To quote my wife and friends who were in the other room, it was the first time in my life any of them had ever heard me truly and honestly yell. It was pretty much five straight minutes of me telling my mom very forcefully that she's GOING to get an alarm system and I was GOING to show her how to use it and I was GOING to make sure she and Dad used it on a regular basis. My mom's in shock to the point where my dad noticed and when he took the phone from her, it was the first time I ever raised my voice at him in over 30+ years about how it's "better to have and not need than to need and not have."
The kicker was when I said "If I told you that _I_ didn't have an alarm system, you'd kick my ass three ways from Sunday because I wasn't protecting my stepdaughter," and that's what made it sink in for both of them.
Three days later my wife and I were there when the new system went in and we spent an hour showing my folks how to use their mobile devices to arm/disarm it. Afterwards my dad said "I was worried that as we got older you wouldn't be willing or would be scared to take charge when your mom and I start to slow down. I'm really proud of you."