Can choosing not to forgive actually lead to personal growth, and what does that journey look like?

Why do people say someone can be nice but not good? I would've thought being friendly but doing bad things isn't nice.
If Trump for any reason lost office, would JDV, with no boss to please, carry on with Trumpian policies? Or would he have his own agenda, and if so, in which direction would he take the country? Would he undo some of the damage or make it worse?