An uncle of mine was a notoriously a ruthless businessman in his heyday and he fell prey to a gift-card scam where he was kept on the phone for 8 hours straight while he did their bidding. We were all shocked he fell for this but then realized the techniques that they use prey upon individuals with inability to deal with stress or trigger anxiety/panic causing them to act irrationally.
As I age, I've noticed similar declines in ability to deal with multiple tasks, stress, etc.
A better defence is to reduce the attack surface. While, I have legal financial control over mom's estate, suffering from moderate dementia, I've removed her ability to interact with her finances by removing her check book (she had loaned a large sum to an acquaintance without informing us), lowering her credit card limits, removed access to online banking, maintaining a low-balance checking account. All her expenses are on autopay. She doesn't even think about her finances anymore. Whenever she gets telemarketers, she always says "you have to talk to my son". Once in a blue moon she asks me "do I have money? I don't even know" -- and I reassure her she doesn't have to worry about money.
I've done the same -- 2factor, using disposable credit card numbers, maintaining a separate PayPal-linked bank account separate from my main account etc, text notifications on all transactions etc.
The sophistication and technology being used is also becoming problematic in detecting these scenarios even for highly aware/technical folk.