Addiction is not exclusive to audiophilia - that comes in many flavours and forms of course.
The problem is that upgraditis in audiophilia is cruel. Consider the following:
- The listening experience is completely personal and subject to personal preferences and biases
- The listening experience is subject to the listener's mood, state of mind and level of focus
- The listener can tend to derive emotion from the listening experience, even when trying to remain objective in evaluation
- The listener is subject to the placebo effect of the perceived quality of audio equipment before the listening experience has started
- Sound reproduction quality varies with music genre and recording quality
- There may not be any good recordings of the music/genre/artist/song that you like
- Everyone is a reviewer, some reviewers opinions seem to count more than others and no one reviewer is exactly the same as each other or you
- The difference in perceived sound reproduction quality in technically competent audio devices can be indistinguishable from each other
- It is difficult to maintain the exact same volume level when comparing amps and DACs. Differences in volume levels affect sound perception.
- Dissatisfaction is a vicious cycle that is purely psychological. Then again, so is satisfaction.
All these factors (and many more) influence your enjoyment, listening experience and purchasing decisions. Sprinkle a little dose of neurosis into the mix and you have that hellishly persistent itch that is audiophilia.