>I highly doubt that the HR went from 0 to a hire in <1 week. The hired candidate was obviously already in a more advanced stage of the interviewing process when the OP was asked to make a presentation.

That doesn't change anything. The company had no idea if the other candidate would pass the final interview or accept the offer until the very moment when they did, at which point they would have canceled OP's presentation. And that's what they did.

>They asked for a presentation knowing that there's a very high chance it will be meaningless.

So are you saying the better option would be for the company to say "well, there's a small chance we might hire you, but instead of giving you the opportunity we're just going to go ahead and reject you without even giving you the chance"? No, that's disrespectful.

>They didn't have the courtesy to sit through the presentation they asked for

Telling the candidate to waste their time giving the presentation that they already know won't change any outcome is disrespectful. If that had happened, we would all be here commenting about how the company is assholish for wasting OP's time by making them give a pointless presentation.

You say "strung along", I say "they were willing to give OP a chance at the job even though OP was not fully qualified for it, and when it was decided that the role was no longer available to OP, they told OP that rather than having OP waste their time giving a pointless presentation that wouldn't have changed anything".