Or, they derive entertainment value and therefore add to your list:
4) Same reason that people get caught up with supporting sports teams or athletes (that don't do it simply because they bet on sports teams or do fantasy sports).
If by "other people" you meant all other people--I don't think that's actually true or evidenced here. All of these people have professional stakes which are in play in a heated debate they're having with a very small number of other people who also have professional stakes. But I'm sure Gruber and Topolsky and others go home and have lots of relationships with people that do not involve any of this.
I feel similarly about "think about": as heated as this language is, I don't know that we can easily characterize what Topolsky thinks about Gruber and Siegler overall.
I took that quote and that post to refer to the negative implications of treating people differently based on personal preferences.
>If by "other people" you meant all other people--I don't think that's actually true or evidenced here.
Not all encompassing "all", but it happens quite a bit. Many a "flame war" have stemmed from something as trivial as personal preference. The very example we have is a public example, which is good for outlining the issue, not defining it. I understand these people have professional reasons to pick one over another. I understand why one would defend their preference aggressively. But as the article implies, there are ways of doing so without putting down the other person for a difference of opinion. That is the overall lesson.
1) If the product maintains a good reputation, early adopters will have been seen to have good taste or perception, which is socially valuable.
2) If you have developed expertise in a product that grows in popularity, you have the potential to be a resource to late adopters. Whether that potential is exercised or not, it represents a certain amount of social, and in some cases professional, capital.
3) If your product becomes disfavored, it may become unsupported. This means that you likely have a shorter usable lifetime for the device, fewer support options (official, 3rd party, and community), and fewer future options for peripherals and software. Each of these network-value losses means less personal wealth.
Also, there's some evidence (see e.g. http://en.wikipedia.org/wiki/Endowment_effect) that people often overvalue past purchases even beyond the level that rational assessment would indicate.