They don't agree with you. Why should they take the time to internalize what you think a Trump presidency would mean, if you're wrong?
Have you followed all the problems related to people losing their jobs because of tweets, and Nobel laureates losing their jobs because of jokes that got blown out of proportion?
This is not quite the same as that; Trump's statements are not one-off tweets or jokes.
But you assume Trump's statements are literally what he wants to enact. Only #nevertrump actually believes that; everyone else thinks Trump is making statements that are just the right-wing version of Open Borders and Universal Income, and Trump and his supporters actually expect those radical right-wing positions (consider them an initial negotiation position) to be negotiated down to something centrist. They don't want all Muslims banned (well, some Trump supporters do, but not many), nor an economy-damaging trade war with China, nor a literal wall running the entire Mexican border, nor refusal to defend NATO allies. What they do want is some respect for enforcing existing immigration laws (congress made it illegal to immigrate by walking across the border, but the Democrat propaganda seeks to frame Trump as a bad person for suggesting enforcing the law Congress wrote). They want some attention paid to long-term economic consequences of outsourcing so much production, and restructuring the costs of the U.S. playing World Policeperson. They want some indication that the government is aware of the difficulty of "vetting" immigrants from a war-torn region without stable government, and that there are social and political externalities from accepting not-well-vettable immigrants when those war-torn regions are known for terrorism (that we may or may not be funding to try to topple Assad), and when even those who are not "terrorists" have what most Americans would consider an undesirable propensity for supporting things like Sharia law.
You and other Thiel-haters reject the principle of charity as it applies both to Trump and to Thiel; you paint a caricature of someone's positions, and go on a witch hunt against anyone who supports those people. When that isn't enough, you go on a witch-hunt against anyone who associates with those people. I consider that dangerous and politically damaging. Obviously everyone has a right to express their opinions, and to choose their associations, but that presumes some level of respect, caution and restraint that is not generally being shown by modern liberals.