Why is it that telemarketers or people from the phone company (say), feel the need to badger the elderly? Have you ever encountered this?

So, my Dad is on his own. He lives in our childhood home and he takes care of all of his bills. My Dad is 73. This past week, I have been coming by the house to help clean out the basement. When (I’ve been) there, my Dad has been getting calls from Bell Canada and his cable company. He owes nothing to either of them. His bills are always paid on time. I listen to him while he is on the phone. They pester him to buy stuff, add more features and whatnot. He tells them no, but, they go on and on. At one point, he handed me the phone, so, that I could hear the person on the other end doing their spiel. They were rude and pushy. I then spoke to them and said “Listen, he’s not interested. He told you that he was not interested a few minutes ago. Stop calling or I’ll report you”. I won’t put up with that shit.

If you’ve been through this, how did you deal with it?