It's an effective two-party system with unfair weighting utterly colonised by some of the most well-invested in propaganda efforts in the world.
People who report that they're Republicans very frequently flit wildly on whether the country's on a good economic trajectory based on whether Republicans are empowered, seemingly completely independent of any other metric.
Maybe not overnight, but all friends begin as strangers.
The issue with the US isn't exactly Trump himself, it's that nearly half of American voters endorse him and that there's a line of vying inheritors for his brand of politics forming.
Trade, foreign, and domestic policy in the US can now be reasonably assumed to turn on a dime every few years, and that's exposure to risk that nobody wants to deal with.
Even within the four years, we're like three months in and the man is rapidly changing his mind on the fundamentals of international relationships. Whether he's manipulating markets, trying to force capitulation somehow, or something else is irrelevant - other countries are more stable and those relationships can provide what's needed.