I remember bringing home my first HDTV, it was only a small 720p TV but after hooking my 360 up to it I was amazed by the clear picture, later on I bought a big screen 1080p when there was more full HD movies and tv seasons available.
Now we almost all have Blu Ray, 1080p tvs, and maybe something you use for a media center. There is so much HD content it has overtaken SD in a lot of places and is now the norm.
I don't have crazy amounts of money for a 4K tv now but I would rather wait until it's a lot more popular and has wayyyyy more content and support, I saw a 4K tv running a true 4K demo video running at an electronics store and was amazed by the clarity, I wasn't to surprised to hear the TV had been gawked at by everyone who came in but they hadn't sold any of the few 4K tvs they ordered, people just don't see the value in a 4K tv that only has 1080p content.
Sure there will be early adopters but most people won't have enough true 4K content available to them to justify such an expensive purchase for years, and by then 4K tv and monitors will be better and cheaper, 4K is the future but I think people who jump in to early will feel burned when much better and cheaper models constantly enter the market afterward.
I'll grab my 4KTV when most movies and tv shows have 4K versions, Although if a decently priced 4K monitor were to arrive I might save money for a couple seriously powerful graphics cards and see how games look in true 4k as long as they run at 60 + fps, we choose quality over performance too much