And was getting rid of Obama healthcare, meant to benefit the poor?
There are many who would argue and believe that Obamacare is pushing up the costs of medicine to the extent that the insurance companies backing it are unwilling to participate which pushes up costs further leading to a rationing of medicine. The policy of Ibamacare is sold to many of the poor voters as something that will go bust leaving them with no health care. That I think people are wrong to believe it doesn't mean that those voting Trump are mainly or even in a large part what would normally be described as right wing extremists.
For millions of people in the U.S., there is the experience that the good years in the economy passed them by, and the bad tears hit almost solely on them. In a culture where aspiration is central to the mythos, Trump can and has plated the outsider, someone to challenge the beltway politics of fixing and dubious deals.
It's essentially a trap which bolsters his support to call them in the main alt right extremists. Just as we had in this country with all Brexit supported are racists because it makes people feel that questioning the status quo is being told you are a Nazi, and they know they are not, and they see plenty of reasons to question the status quo.