I would be attempting to think ahead while asking myself what I would be doing in a few years time when considering what hardware I want to purchase. In other words, while you're playing simple games that aren't graphically intensive now, do you think you will still be doing that in a few years time? Do you see yourself becoming increasingly enthusiastic about playing the latest games at the highest resolution settings? How long do you want to keep your monitor before picking up another replacement? 2 years? 5 years? 10 years?
If you want a 4k monitor feel free to pick one up, it'll be pretty future proof and at the very least the simple games that you're playing now will look better.
But do try to check if your eyes can actually detect any difference in higher frame rates and resolutions if possible. No point in getting 4k if you can't notice the jump in clarity, and there's no point in getting a 120fps monitor if you're like me and can't see any difference between 60fps and 120fps.
As for my own experience - I picked up this 4k monitor 5 years ago along with a GTX980ti. I've been pretty satisfied with my decision, and I've been playing games at either 2160p, 1890p, or 1620p ever since. I don't intend to replace my monitor for a long time.