Do you have/collect any 4K physical media? I recently started to collect again after years of only streaming. I wasn't sure it was worth the upgrade, but after watching a few movies on my new UHD player, it was definitely worth it just for the picture/sound quality alone.
I started by writing a list of movies I'd like to own, and would actually watch more than 1 time. Once that list hit over 100, I figured it was worth it (I've bought 10 UHD disc's now, and have another ~150 on my list).
Streaming is great for convenience, but doesn't do the sound/picture any real justice. There are tons of movies/media available in 4K now.
At the end of the day, only you can decide for yourself whether or not the cost of upgrading justifies the amount of usage you'll get out of doing so. I've gone down the rabbit hole myself, but I'm still not 100% convinced I'll get my "moneys worth". Only time will tell.