The elderly still want autonomy, and the scams adapt and change faster than education can get most of the elderly caught up to the risks. That's entirely removed from the technical aspects, which are a whole other level of education on risk. Scams always will move faster than defenders and efforts to block them.
All of which are divorced from the real problem, which is isolation of the elderly. The elderly often jump in to these scams simply because they just want someone to chat with. Many romance scammers will report that all they do is strike up a conversation with people, and quite often that's all it takes to get in deeper on an emotional level than the victim's entire family. The family treats this like a money problem, when it's an emotional gap the scammer is exploiting.
I had a neighbor once who was so poor her gas got turned off. Blind due to diabetes. Still managed to send half her meager social security check to a televangelist, because the televangelist was on TV in her face all day, and her family visited once a month. The elderly were prime candidates for 1-900 psychic numbers for decades because it was someone to talk to. I imagine your grandfather wanted to feel like he was helping someone, and scam letters gave him a perfect way to convince himself he was doing exactly that.