Why was the popular vote so close in the US presidential election?

Regardless of the eventual winner, one thing that stood out was how close the popular vote was. What does it imply that the polls, predicting a Biden win with up to 10% more votes, were wrong. Why were many voters afraid to tell even an anonymous pollster that they preferred Trump over Biden?

What we choose to believe the reason to be greatly impacts how we, as a country, proceed.

• We could choose to believe that the Trump supporters are simply closet racists, sexists, and bigots who secretly want to support one of their own - doing so reaffirms the narrative that America is a terrible place.

• Or, we could choose that they were not buying the narrative that America is fundamentally flawed with racism, sexism, and other forms of bigotry .

• Or, we could choose that they simply believed that Trump was a better choice despite the best efforts of mainstream news, social media, and the entertainment industry to highlight his flaws - factual or not.

Especially for Biden/Harris supporters, how to move forward really depends on what was learned from this election. If it's the first option, perhaps Trump supporters simply need more CRT (aka, racial sensitivity) and similar training? If it's the second, perhaps it's a time to re-examine some of the assumptions of the progressive movement? If it's the third, perhaps these organizations should try harder?

What do you think?