Typical movie theaters use 4k today, and 2k (very close to 1080p) less than 10 years ago. For their huge screens. Of course the bitrate is very high, "up to 250 Mbit/s" (https://en.wikipedia.org/wiki/Digital_cinema#Technology_and_...)
For small text and fine lines such as used in a close-up computer monitor, 4k+ can be very beneficial. But for video, it's marketing, and a costly waste.
1. http://conversation.which.co.uk/technology/many-blu-rays-no-...
1) Most digital photos are 4K - a 4K TV is ideal for viewing them. 2) Youtube videos 3) This video 4) Other sources of 4K video that are coming online right now.
Sure, you might not get 100% of the benefit of your 4K TV for ten years, but that doesn't mean it's not worthwhile.
In my case I had a terrible old TV, so upgrading was a no-brainer.