You're assuming that 318.9 million people in America
actually vote. They don't. Big cities tend to get high voter turnout (obviously).
120,000,000 people voted this election..... If you cater to big cities and tell them what they want to hear you can
get at least 23,000,000 votes (20% of the popular vote) out of them. If you don't see how big of a dent that actually is capable of being, you don't understand how elections work.
"Most of the country's states are decided before the election even starts."
^ doesn't make sense and clearly wasn't the case in this election.
Zoomed in on the important part of the picture for you to read again:

The states being Nebraska, Montana, Iowa and Idaho
all of this without mentioning
we aren't a direct democracy. We're a Republic. We always have been.