People's personalities can be determined after a period of time of seeing/studying them and are generally "set-in-stone" when older (like Trump at age 78). As such, determining what he is likely to do (or will do) has a very high degree of probability.
It has already been determined by a lot of renowned psychologists that he is a narcissist and that means he does not care about others (only about himself) and that he only helps others when it is personally helpful to himself.
There are a lot of things that Conservatives want and Trump is offering those to them because it helps him and raises his ego. Nonetheless, the narcissistic personality does bring a lot of big negatives as narcissists always blame others when things go wrong, narcissists believe they are better than everyone and narcissists are selfish to an extreme degree. This means that even if some (or most) of the things that the Conservatives want and will get with Trump, the costs of getting them is way too high.
Leading a country has a lot of factors involved that require the ability to compromise, the ability to understand reality, and the ability to be humane and defend human rights (which is something our country has been #1 in the world for centuries). A narcissist does not have the ability to do any of those.
As such, the "probabilities" are high that Trump will end up doing big and permanent damage to our country. The thing that I think about and the reason why I try so much is that under these circumstances, prevention is the only thing that will work. Taking the chance and waiting for it to happen and trying to change it then, is not a good option.
This is the reality of the situation, or at least it is more than 90% probable. I cannot accept such a high probability, especially when there are other options that have a smaller probability of causing so much "and permanent" damage.