If Trump wins the Republican nomination, that leads to one of two results and both are bad, in my opinion.
If Trump wins, which I think is 50/50 depending on the Dem opponent, he goes for an even bigger grift for him and his friends without fear of repercussion (what impeach him again?), and probably starts at his inauguration speech talking about a mandate and he should really have a third term since he had one stolen from him. Four years of him not leading but instead playing games in an attempt make money and gain power. Everything will be about him and never about the country.
If Trump loses, still 50/50, then he immediately claims it was stolen again, no matter the margin of defeat, fires up his base to storm local, state and national building in order to "save the country and steal back the vote". Have new hats, new flags and new emails asking for support for his legal lawsuits to win back the country. We will see Trump 2028 stickers before anyone actually calls the election for the Dems.
I would gladly take a Republican moderate who can lead with some normalcy over either of those choices.