I think the psychological need to have the best possible experience is an element of most enthusiasts' areas of choice, and this results in small or even imperceptible improvements being perceived as worth the substantially extra cost.
A classic example is audiophiles, many of whom can't actually tell the difference between lossless and and a super-high-quality lossy format, yet are addicted to checking the bitrate or whatever and aren't satisfied until they know
it isn't flawed, regardless of whether or not they can pick out the flaws; this can lead to buying incredibly expensive headphones and lord knows what else. I have to admit I've fallen victim to the whole bitrate thing and feel a bit down if my mp3 isn't 320kbps.
Gaming is another area where people spend huge amounts of money on minimal performance increases so they can run the absolute latest games on full settings, which of course moves on every few months and becomes very expensive. But for someone who cannot bear to play with a poor frame rate or turn the graphics down, doing so makes them deeply unhappy.
So, like any other medium, television and film is an area where people will always shell out for minimal quality improvements regardless of whether or not you personally think it's worth it. And more often than not, even they can't really see the difference. Or if they can, it doesn't make as much of a difference to their experience as they think it does -- it's simply having that cutting edge of technology that they desire.
But hey, if you have the money.