Regarding your edit (i. e., what would it take for Trump followers to change their mind), go hit YouTube with a search for “Jordan Klepper fingers the pulse” and watch some of those. A more recent one, in which he speaks to Niki Haley supporters, demonstrates what are likely “more reasonable” Republicans regarding Trump, and probably best answers your question. Most feature him speaking to Trump supporters at Trump rallies. One features him talking to supporters during (yes, you read that correctly) the January 6 insurrection. Watching these will help understand the entrenched mindset. Hilarious and horrifying.