Let's look at how the meanings of certain words have changed within the only community of language users relevant to Hit Self-Destruct: gamers. You may have noticed critics and message boards patrons using the phrase 'tech demo' as a pejorative. Where it was once a straight-forward descriptor, 'tech demo' can now imply that a game is full of graphical and programming tricks but low on substance and gameplay. Example: "Crysis is a tech demo" is an insult, whereas "This Unreal engine tech demo is a tech demo" is an objective statement. In an earlier, similar study of the cultural vernacular of video gamers, sociolinguist Duncan Fyfe examined how the words 'journalist' and 'amateur' were used not to refer to professional status but as "endorsement[s, or as] a statement of preference." 
In this sophisticated etymological investigation I don't intend to campaign for the preservation of tech demo's original meaning. Instead I will help ruin it by diluting the term even further.
For instance, if you think the guitar solo in a rock song is a little too prominent, call it a tech demo. "Sure, it's an epic jam, but the song is such a tech demo." That's a serviceable cross-media translation, but I'm interested in really obscuring the etymology of 'tech demo' and coming up with less and less sensible definitions. Earlier this year I borrowed the word 'supermodel' from the fashion industry to mean games with high production levels, critical immunity and a devoted fan following.  It seems appropriate, then, to return gaming technology to the fashion world. A 'tech demo' is someone whose only professional value is to showcase a new, and possibly radical/experimental clothing design. These women are tech demos:
Helpfully, this new definition also serves to distinguish between your everyday department store models and your charity-minded social advocates and talk-show perennials i.e. Linda Evangelista.
Alternately, a tech demo can be considered synonymous with fashion plate, as it alludes to one who is quick to adopt the latest, hippest styles or accessories. Many years ago, this gentleman would have qualified as a tech demo by virtue of the once-novel reverse positioning of his baseball cap:
Today, one might refer to these three friends, pictured below, and the population of Williamsburg, Brooklyn, not pictured, as modern tech demos.
I hypothesise, however, that 'tech demo' has widest resonance when it refers to the kind of person who is basically flighty in nature. When you take an online personality quiz and it says you are a tech demo, that means that you shortsightedly flit from one attraction to the next, touting each phase proudly but never with any lasting sincerity. It is consequently hard to pin down who you really are or what you really care about. The tech demo chases what is new, hip and fun, committing to little and always moving on. You are the kind of person who switches majors after two years because they are bored.
Time's up. Pencils down, papers up front, then leave the lecture hall for the final time, walk straight back to the dorm never looking back. I'll get a C- for this if I'm lucky. In any event, I leave the ephemeral majesty of tech demo behind me. It will remain forever isolated within some university's archives never to be seen or used again. In the classic tech demo manner, it will be forgotten and passed over for something new. That is the way of things.
Or is it?
(The AV Club, The Huffington Post, YouTube)
Spread the word. I started.
 Fyfe, D., 2008, You're Not A Journalist, Hit Self-Destruct, accessed 29 August 2008, http://www.hitselfdestruct.com/2008/06/youre-not-journalist.html
 Fyfe, D., 2008. Supermodel Is One Word, Hit Self-Destruct, accessed 29 August 2008, http://www.hitselfdestruct.com/2008/06/supermodel-is-one-word.html