You took the thoughts right out of my head.
He had to begin somewhere. He was very astute to choose "immigration" as the trigger for his base, following the horrendous mess fostered upon the nation by Barack Obama for eight years.
Today, he's converted millions of voters to his side. (See TBR, for example), and given the alternatives available to them in 2020, he's going to stake a claim on them before the Democrats will.