Almost realistic enough
BBC feature on who gets to be president and how the election works. Allegedly aimed at British youngsters. Surprisingly realistic, especially about the intrinsic corruption of the Electoral College. Most US descriptions focus on the old fake selling point that the EC "gives more power to small rural states."
That was never the purpose, and it's wildly untrue now.
A much simpler answer would be more comprehensible to Brit yoots.
You get to be President the same way you get to be Monarch in Britain, by belonging to the dynasty. The US dynastic setup is sloppier. We don't have a single permanent dynasty; instead we have gang wars between short-lived competing dynasties, as happened in Britain before Tyrant Elizabeth 1.
Occasionally a non-dynastic is placed in office when the heir of the dominant dynasty isn't ready. Hillary was used up and Chelsea wasn't ready, so Trump was installed as Regent to maintain the dynastic policies while besmirching all opponents of the dynasty. Chelsea's path will be easier after all opponents have been exterminated.