Whats enough for my build?

[Soulcatcher668]

Buying the top tier video cards is never in the price/performance sweet spot. Only you can decide if it is worth the money.

For me, I would rather have lower settings and stay above 60 FPS than have to deal with 35 FPS. That is console pleeb territory.

 

[GTXJackBauer]

My GTX 1070 G1 is heavly overclocked @2133mhz, a game like BF1 or GTA5 on 4k ultra setting, around 35-45fps (depends)
Do you all think GTX 1080 Ti is worth the money to upgrade or just FKKK it for now?

As stated by Soul, that's up to you. I personally would go with a GTX 1080 Ti if I knew I'm going to be sitting on 4K @ 60hz for a long time and possibly grab another one used down the road for a good price if need to be once games got even more demanding to keep around a constant 60 FPS. If that wasn't the case and I was planning on gaming on 4K 144hz, than I would most likely wait on for the next line of GPUs or wait for the next Ti which I think might be around either the bottom half of 2018 or 2019. But these days, AMD seems to be back on the map so anything is possible.