That is surprising to me. I feel no need to go 4k as of yet. I've toyed with it but the wife is against it as well. Sigh...
It's mostly just getting a new TV, not because they actually cared about 4k. These days, all but small and very inexpensive TVs just are 4k. You buy a 55" TV (the most popular size) and you are hard pressed to find one that isn't 4k. Even a bargain basement Chinese government brand (Hisense is owned by the Chinese government) $280 55" TV is 4k.
So I don't think tons of people are really going out saying "man I need to get 4k!" rather they just want a bigger TV, or newer TV, or a TV for another room and it just happens to be that the TV they get is 4k.