My Mum has dementia. Not overly bad, & she still recognises my partner and me, but her memory, short & long-term, is effectively gone. Surprisingly she remembers some things from the past as well as the recent past, but generally there's nothing there...and she is aware of such lack. However, there were some dreadful flaws with her when her mind was acute, leading to a distance between us over many years. Since her dementia, she is a different person almost completely, a mother I can relate to as my Mum, rather than someone for whom I had scant respect (yes it was that bad). I now treat her as one should treat one's mother, with love, kindness and compassion at her medical plight.
With Trump, it comes down to humanity of those who view him. Even if you have suffered at his hands, dementia changes people into another entity entirely. Of course, they could morph into a gibbering, incoherent being needing close care and attention, or any one of a myriad of symptoms which appear to manifest themselves. No 2 cases appear alike. For all his bombast, misogyny, racism, violence and fake tan, Trump is still human and if his hour of medical and psychological infirmity arises, we should not lower ourselves to his (present) standards.
Dementia takes control of lives and bodies. Dementia, in 1 way or another, will eventually kill a person, but along the way, they are inexorably altered. Should Trump descend down this path of many hells which is dementia, he *will* change. As humans, it is incumbent on society to show mercy and kindness. It's not 'turning the other cheek' to Trump. It's showing him by example and doing what he lacked before dementia set in.
That, folks, is karma & a sort of revenge!