I feel like Trump self-destructs on TV every day. In 2016 he repeatedly threatened to jail Hillary Clinton and happily enabled his supporters to chant "lock her up" at his rallies. That ought to have been its own self-destruction, yet he got elected president. This week he's calling into TV shows claiming he never said that (even though there are video clips of him saying it), which ought to be the self-destruction of an obvious lie, yet he's indestructible. On the surface, his messaging angle seems to be: It would have been "terrible" for me to lock up my opponents in 2016, but now they REALLY deserve to be locked up. His principle (or lack thereof) is that it's bad/illegal/dictatorial to do things that are bad/illegal/dictatorial, unless at any given moment he feels in the mood to do it, in which case it'll be his prerogative to jail a political rival. This ought to be a self-destruction but it's just a normal interview for him.

I believe there's literally nothing Trump could say on TV that would make him lose any measurable support.

Same for JKR. If she literally said the magic words "I hate and fear transness, so I hate and fear all trans people," her supporters would say, "Nothing about that sentence is transphobic. When has she ever said anything transphobic?" It would just be a normal day for them.