Sure, a tiny speck of dust can affect the whole universe, according to my Zen master.  But I fail to see how Trump's (arguably racist) edict on US immigration actually affects market values.  For that matter, the only major effect government decisions have on my investments are the hysterical reactions by investors that over-react to the daily news.  In those cases, prices soon bounce back, so it only really affects day traders.

It's the decision of business leaders that matters most.