The determinants of fanatical product support

A rambling grad student offers a few reasons why such things as trucks, operating systems, and video game systems develop fanatical product support while other things such as couches do not. He lists 5 candidate explanations:

1. Price: The big ticket items are more likely to develop fanaticism - works for trucks and electronics, but furniture costs a lot, too . . . why does no one even claim LaZBoy roks and Pottery Barn sux?
2. Social visibility: Maybe people are more likely to be fanatical with high profile visible goods - but that kind of fails when it comes to computers and video game systems.
3. The people that buy them: Maybe people that consume these particular goods are just the kind of folk that feel the need to identify themselves with one side or the other (or at least the type that are willing to broadcast their product choice and publicly berate all other choices)
4. Longevity: Maybe the longer timeframe investments warrant more fanaticism to justify purchase . . . but the cycle time on electronics is far too short for that rational.
5. Amount of user interaction: Electronics and trucks both have high user interaction time. Maybe items with a lot of product/user interaction require greater mental justification, and thus support higher amounts of fanaticism.

#5 is by far the most interesting and clever hypothesis.

Nevertheless, I think the answer is a twist on #1. That is, fanatical product support is driven by price relative to income. I imagine that those who are fanatical about trucks first purchased their truck when its cost was a large share of their income. More generally, it's probably stronger for people with low income. The same for videogame systems and computers--it develops for young folks with little disposable income. This also explains why no one cares about couch brand names. When it comes time to buy a couch, it tends to be a drop in the bucket.

I'm sure you have many personal counterexamples to this explanation. I also know plenty of folks who are well-off yet fanatical product supporters. This is easily explained by a gravity-type model. Once a bunch of people have sorted into their respective camps, there is pressure for others to join rather than to remain agnostic.