Yup GPU beyond RTX5070ti is really not really worth it unless you have a lot of money to spend on half of your pc budget then sure go for it
Better spend the rest for CPU like 8700x3D.

High vram doesnt mean it will be use for gaming all the time, the advantage of having higher vram are when applying other setting like high texture on graphic setting usually will be consume a lot of vram or using for local AI stuff. Usually the cpu will start bottleneck first if you going for higher end gpu.

5070ti are good enough even for 4k gaming, because when you spend more money pass 5070ti price/performance are not really there if you have a budget tu spend. That why go for better CPU since GPU always the faster one to to be updating in future.