Wow! what a loaded question from Quora. I would love to answer it there, but it seems a bit pointless for a few reasons.
The first is that the first answer is pretty good for someone unfamiliar with the US political process. The second is that any answer would be buried in the abusive answers he received.
Anyway, I'm guessing this person has voter's remorse, which happens in a system where someone has to pick a "lesser evil" (or a Scylla and Charybdis election).
First off, I would point out that Hillary Clinton won the popular vote with one of the largest margins ever. Or conversely that Trump lost it with one of the largest margins ever. The US is unique in having something called the Electoral College, which means the popular vote is pretty much meaningless. Clinton would have had to win the popular vote in at least Florida and one of the following states: Michigan, Ohio, Pennsylvania, or Wisconsin (i.e., win the popular vote in Michigan, Ohio, Pennsylvania, and Wisconsin) to have won in the Electoral College.
The Electoral College is something that truly needs to be abolished.
But you can feel easy that your one vote isn't what cost Clinton the election. That's because unless your vote wouldn't have changed too much unless you happened to live in Florida, Michigan, Ohio, Pennsylvania, or Wisconsin. Even then, one vote seriously wouldn't have changed the outcome of the election. But that is an oversimplification based on possibilities of Clinton winning any of those States.
Also, how did the election turn out in your state in regard to the Electoral College votes? You are in the clear if you lived in one of the States where Clinton won the Electoral College votes ("Blue State") since your vote didn't count: Clinton won those anyway.
Likewise, your vote didn't really mean much if you were in a "Red State". It wouldn't matter who you voted for in that case: Clinton lost.
Still, your problem is an example of why it is wrong to vote against a candidate instead of for someone you believe in. But basing an election on lesser evils means you have to vote for evil.
Sure, you could do what I did and vote for a third party because that party held values you share (or was most representative of your beliefs). The Greens were pretty much what Bernie was promoting: and I had no idea what Clinton was actually for (other than herself).
Did you consider voting for Gary Johnson if you believe in libertarian values?
One nice thing about voting for third parties is that can automatically get on the ballot and in the debates if they get enough percentage of the vote.
Anyway, you should make it clear that the popular vote is meaningless for President in the United States. Also, you should point out that you voted for the candidate you considered the lesser evil. That means an evil candidate still wins.
I voted Green because I don't vote for evil: lesser or otherwise. I also voted for a candidate and party which represents the values I believe in.
So, maybe you might want to look into a third party candidate next time.