Some of that obviously stems from Trump not having concrete convictions. But I have thought all along that he might also be going by the instincts of having been a businessman for over 50 years. He's been a hardnosed salesman and negotiator for all those years, and it is what he knows best- not politics. When I meet with our advertisers every year, they throw on the table an outlandish number, and the dance begins. I throw out my own number which I know is way lower than they would ever accept, and we meet either meet at a comfortable level acceptable to both parties or they lose a client and I lose a method of advertising. I am not sure, but I suspect that it might be in Trump's nature to start off with the outlandish, with full acknowledgment that it's just a starting point for what will later be renegotiated. Maybe?
Just as an example, when Trump said he was going to build a tall beautiful wall, that might very well be what he would most want, but had in the back of his mind that he probably would not get. He may have known that buses shipping out millions of illegal immigrants was never going to occur as well. I sure did. But if he winds up having a much tougher immigration policy, perhaps ending sanctuary cities and building a wall where most feasible, as well as getting rid of the gang related criminal element that illegally resides in the country, I think the vast majority of his voters will be satisfied with that result. It's much better than keeping the status quo.
If you say promises shouldn't be made that are not meant to be kept, I would whole heartedly agree. But another person on this sight, I have to paraphrase his words, said something on the order of "telling the truth only matters if you don't want to win". Unfortunately, there is a lot of "truth" in that statement.