Donald Trump would be an absolute disaster of a president — so bad it's almost impossible to grasp.
Trump's real estate development record is mixed at best, and several forays outside property ownership and management — be it education, food, or gambling — all ignominiously collapsed. At bottom, the Trump business formula is simple: Borrow a ton of money, invest in real estate during a boom, cash out the equity to a protected location, then declare bankruptcy after the market turns. This is an effective strategy when conditions are right, but it is purely taking advantage of external conditions. No business is really happening. It's pure parasitism. (It's unclear whether Trump even understands this is his strategy.)
Third, domestic policy. Trump does not have a remotely comprehensive policy platform. He clearly has no interest in building one. He clearly is unable to build one.
Trump constantly (and inadvertently) reveals his staggering ignorance of the most basic facts of government and recent history. Trump didn't know that Russia had annexed Crimea. He didn't know what Brexit was. He didn't know that the Trans-Pacific Partnership does not include China. He is very obviously a guy who gets his news from half-watching cable TV and the racists in his Twitter mentions.
When NBC News attempted to compile a list of every Trump flip-flop, they came up with 117 major changes in positions — and that's likely an underestimate, since it was published a few days ago. Even on his signature issues — the border wall that Mexico is supposedly going to pay for, and banning all Muslim entry into the United States — Trump is all over the place. One day it's round up and deport all 11 million unauthorized immigrants and ban Muslim immigration, the next it's a path to citizenship, and only partial Muslim restrictions, then back to mass deportation.
Insofar as one can discern any sort of domestic agenda through his blizzard of nonsense and rapidly shifting positions, Trump's favorite things are discriminating against Latinos and Muslims. The political forces behind him include a sizable fraction of straight-up white nationalists.
Over and above his threats against a free press, Trump's campaign has been the most overtly violent in living memory. His rallies have seen a steady stream of violence since early in the primary — most recently, a Trumpist socked a 69-year-old woman on oxygen right in the face. Trump has incited and encouraged this violence, telling his rallies that violence is acceptable, refusing to condemn such behavior when journalists ask, and even saying he might pay the legal bills for a man arrested for allegedly assaulting someone at a rally (though Trump, as usual, later insisted he had done no such thing).
Trump's campaign has accomplished the greatest legitimization of political violence since white supremacist "Redeemers" violently overthrew democratically elected Reconstruction governments in the 1870s. He represents a movement of proto-fascism that will probably endure long after he is gone.
Trump's foreign policy might well be corrupt. As Kurt Eichenwald details in Newsweek, Trump is involved in dozens of shady business and real estate deals overseas through the Trump Organization — in South Korea, India, Turkey, the United Arab Emirates, Azerbaijan, Russia, Ukraine, and elsewhere. It would be almost impossible for Trump to conduct foreign policy without hitting conflicts of interest. Not that he would care about such things; instead, he would almost certainly attempt to leverage the power of the presidency to secure more lucrative deals for himself. Profit and self-promotion are the only consistent notes in the life story of Donald Trump.
Scholars argue that democracies are more stable than monarchies in part because they can survive a bad leader or two. But the flexibility is not endless. Donald Trump might well bend the rickety American constitutional system past the breaking point. Don't let him.