Perhaps because everything is built on top of everything, so an interesting story can always be made of someone responsible for the building blocks.

Thought experiment. I remember FOV2GO (very cool project), but the iPhone was arguably integral to its creation. Was it though? I'm sure the members of the iPhone team would think "yes" (as 99% of the actual manifest technology is iPhone in this device), but the "creator" might think "no" (as the last 1% is what differentiates it). The "true" answer here is not important, rather the understanding that everyone probably overestimates the value of their own contribution, and underestimates the value of others' contribution. Especially because when you discover/invent something that afterwards seems obvious (arguably the most important discoveries/inventions), then it seems silly to give someone credit for it. The Oculus guys may think of the FOV2GO stuff as "obvious" in retrospect, and the actual hard work being the device they shipped with the better sensors and associated toolkit.

If I now choose to make an Oculus competitor to take on Facebook, should I pay the original Oculus team "to give thanks"? Should I pay the professor? I think a lot of people at this point would say "no", which is strange because it doesn't seem like a different case than Oculus vs. professor.

I am not sure if the professor is actually a founder, but more like the basis of the foundation. I don't know if the students ever paid their professor and the lab for the experience and idea. I would, honestly. Giving back a few million dollars back to the lab and give some equity to the professor, invite him to the board.

I suspect a few reasons:

1. The professor is not interested in the profit. He just loves what he does. Or he has no intention of taking any credit. When you are a famous inventor in your field you don't need anyone to back up your title.

2. He did get his fair share. Or he's working on other things with Oculus behind the scene, but not publicly acknowledged (which is weird).

3. Like most tweets the notice/rewteet count is often zero. We just don't hear about it. (Though in the case of Professor Bolas his website doesn't mention a thing about Oculus).

4. I don't know anything about FMX conference but maybe the professor wasn't invited?

5. Companies don't feel they are obligated to release everyone's name. In particular, they probably think basing on public works (published papers and blog posts) holds them no obligation to credit anyone.

But do we know if the founders ever credit the professor in public? I am not going to watch every interview, but my feeling is yes, at some point. I don't think anyone could say "they invented Oculus out of the blue".

This is also a private matter. Maybe they had problems with each other, or they settled this privately already ("I don't want any share", "don't mention my name", etc)

Inventors might not want fame. The entrepreneurial, publicity-seeking ones are unusual; but the ones we hear about.

If he patented it, he'd get licensing fees (I'd go royalties myself). Usually, anyone called an "inventor" patents their inventions (especially if they like wealth). Even Buckminster Fuller did.

The courtesy of asking should've happened though.

Because it looks really bad to the public face person to not give credit where credit is due.

You're assuming there was no ask. We don't know. I'm also wondering if advisor shares would've been possible.

Probably because it complicates the discussion of the product or company. Don't introduce people to the public if that person has no interest in being a public figure or engaging with media.