You're not alone.
On a good large screen, 1080p is a noticeable upgrade from 720p.
But the distance you'd have to sit at, to get much out of 2160p over 1080p, is just way too close.
However the High Dynamic Range that comes with 4K formats and releases IS a big difference.
On the other hand, storage is pretty cheep. A couple cents per GB really.
But you're talking more about bandwidth, which can be expensive.
But yeah. You're not alone.